Bugs

This page shows a list of all bugs declared using the {{bug}} template that exist and can be reproduced in the latest version of the game.

Page	Description	Platform
? Card	Using ? Card on any activated item that needs a direction, such as Bob's Rotten Head or Gello will still result in the charges being used once a direction is chosen. The ? Card will be used up as well, despite providing no free use of the item.	All
??? (Floor)	Attempting to open the door leading to Hush's room while holding a Golden Key will cause Isaac to walk through the door without opening it, immediately beginning the Hush fight.	All
??? (Floor)	PS4 Mama Mega! cannot be used to open the door to ???.	XboxOne
2Spooky	When using D12 to reroll obstacles; any Movable TNT or Fire Places created within the radius will occasionally spawn as feared momentarily with only the purple tint to indicate the status effect. This effect lasts even on the remains of either object after it's destroyed before the fear effect ends. Corn poops created in the radius are unaffected however the Eternal Fly may also become temporarily feared.	All
4.5 Volt	With 9 Volt and The Battery, the gradual charge of 4.5 Volt is separate from 9 Volt's charge on one-charge items rather than being additive.	All
7 Seals	Each use of Glowing Hourglass that does not move Isaac to a different room from the one he is currently in (such as by teleporting to the previous room then using it again) will duplicate the locusts.	All
A Card Against Humanity	Using this card in the TV room in Home will move the sofa and the TV to the nearest empty space (Which would be where Isaac is standing as that's the only space that doesn't get filled with poop). If Isaac tries to approach where they were previously then he will be violently pushed back. Destroying the poop will return them back to normal. If the poop is not destroyed before sleeping in Mom's bed then Isaac will have to stand below where the TV was teleported to in order to activate the Dogma fight. If Dogma is summoned before destroying the poop then the TV will glitch inside the Dogma fight and push Isaac around, possibly making him touch Dogma and get hit multiple times	All
A Lump of Coal	In Greed Mode, if Isaac picks upA Lump of Coal in a Silver Treasure Room and then fights Krampus,A Lump of Coal may still drop after the fight. Since this item's effect does not stack with itself, this will give Isaac a useless item.	All
AAA Battery	AAA Battery will not contribute to unlocking Jumper Cables despite having the item tag.	All
Abaddon	If Keeper picks up Abaddon, it will remove all of his Coin Hearts but will not kill him until he picks up an item. This still applies if Abaddon is acquired via the Debug Console, but not if the item is picked up normally.	All
Abyss	According to locusts.xml, Ipecac locusts are supposed to explode. This never happens in game; Ipecac only gives a locust that deals slightly more damage and poisons enemies.	All
Abyss	Each use of Glowing Hourglass that does not move Isaac to a different room than the one he is currently in (such as the starting room of a new floor) will duplicate the locusts.	All
Abyss	Mucormycosis' ID is numbered incorrectly in the code, sharing ID 466 with Contagion. This causes Contagion to give 2 locusts instead and Mucormycosis to not give the special locust its supposed to.	All
Abyss	Bob's Curse, Sticky Bombs, and Glitter Bombs locusts explode much more than intended.	All
Achievements	Clear Rune must be unlocked and collected to attain !Platinum God! and The Real Platinum God despite being a Repentance item. This is due to its ID being unused in Rebirth, thus being in the ID range of Rebirth items.	All
Achievements	PS4 If installed, before unlocking it, the 'Challenges' trophy will require completing all the challenges available on the current DLC played instead of the original 20 Challenges.'"`UNIQ--ref-00000004-QINU`"'	All
Alabaster Box	Picking up Bone Hearts while at 12 hearts removes charges from the Box.	All
Analog Stick	Both the eight-directional firing (using buttons) and the full analog aiming (using the analog stick) are unavaliable in any controller mode.	Switch
Angel	Delirium can transform into Fallen Uriel and Fallen Gabriel but they do not have unique Delirium skins.	All
Angel Room	The Found HUD will incorrectly display the angel room chance as 100% if either of the "Blessed" messages appear. The percentages listed in this page are however correct.	All
Anima Sola	If Anima Sola is used on segmented enemies (such as Larry Jr.) and targets one of the middle segments, the enemy will sometimes be split into two after the chains break.	All
Apollyon	Using an "I've found pills" pill will turn Apollyon's head invisible, showing only his face and horns.	All
Apple of Sodom	Converting a heart by buying it will not consume any money. However, Isaac must have the amount of coins needed to purchase the heart.	All
Ascent	Dropping a trinket in the exact same spot as an obstacle may despawn Cracked Key further down the road during Ascension.'"`UNIQ--ref-00000003-QINU`"'	All
Baby	If a Baby, Angelic Baby or Imp tries to shoot Isaac at the same time as it teleports, their shots will be fired without their corresponding animation.	All
Baby	If an Imp is stunned, feared, or shrunken, it will still attack Isaac while running away from him.	All
Baby Plum	Concussive effects don't work on Baby Plum.	All
Backasswards	While entering an exit to the previous floor, if the player kills the process (isaac-ng.exe) during the versus screen before a boss fight, re-entering the game will lead Isaac to the starting room of the previous floor instead of the boss room. This allows the player to finish the challenge pretty easily without any actual fights.	All
Backasswards	Sometimes the layout of the rooms makes traversing to the previous floor impossible. There might be a hole where the light is supposed to be and without flying, makes the run impossible to beat.	All
Backasswards	If Isaac is teleported into the I AM ERROR room on the final floor of the challenge, there will be no exit, making the run impossible to beat.	All
Bag of Crafting	While being controlled by mouse, having both The Ludovico Technique + Pop! will mess up the direction control of Bag of Crafting.	All
Bag of Crafting	In the '"`UNIQ--nowiki-0000001E-QINU`"'Cantripped! (challenge #43), using a Bag of Crafting will crash the game.	All
Bag of Crafting	If the Bag of Crafting is used but not swung (i.e., is being held overhead) while returning from the Mirrored world, Isaac will not go back to normal, and will still have the properties of The Lost (flying, Holy Mantle effect) when returning. This effect persists across floors, but Isaac will turn back after some time.	All
Batteries	If a Golden Battery appears in the Abandoned Area before the Mother's Shadow chase, it will despawn for the floor, as the room configuration is changed when the chase begins.	All
BBF	BBF sometimes does contact damage to certain enemies without exploding. [Check ingame]	All
BBF	BBF can get stuck in corners in The Beast fight.	All
Bedroom	If you use The Poop on the middle of the carpet and blow it up with a bomb, the trapdoor will not appear.	All
Beggar	Touching a Battery Bum while it is giving Isaac's active item a charge will grant another charge. Multiple additional charges can be gained this way.	All
Beggar	Will not pay out correctly when trying to gain charges as Bethany.	All
Best Friend	Gurgles, Splashers, Boils, Guts, and Sacks are immune to Best Friend's explosion.	All
Best Friend	Doubles when Multidimensional Baby passes through it.[citation needed]	Switch
Bestiary	The Bestiary is bugged with bosses that have multiple parts (such as Larry Jr., Pin, The Hollow, and so forth). For Pin, The Frail, and Scolex, each body part counts as an encounter and a kill. For Larry Jr. and The Hollow, only their heads count as a kill but each part counts as an encounter. Satan kills are not registered	All
Bestiary Repentance	The Bestiary is bugged with bosses that have multiple parts (such as Larry Jr., Pin, The Hollow, and so forth): For Pin, The Frail, and Scolex, each body part counts as an encounter and a kill. For Larry Jr. and The Hollow, only their heads count as a kill but each part counts as an encounter. Satan, War, The Matriarch and Dogma kills are not registered.	All
Bestiary Repentance	The Visage's mask is not included in the Bestiary (only the Heart is), while both of Mask of Infamy's halves are included.	All
Bestiary Repentance	The Sin Collector achievement can be obtained without a full Bestiary. It requires 2 entries less than what is actually featured.	All
Bestiary Repentance	The Bestiary counts every time Delirium changes forms as separate encounters.	All
Beth's Faith	Each use of Glowing Hourglass that does not move Isaac to a different room from the one he is currently in (such as by teleporting to the previous room then using it again) will duplicate the wisps. Any extra wisps created from duplication on a filled ring will appear at the entrance of each room Isaac enters and shoot in the direction Isaac is currently shooting.	All
Big Horn	If The Boomerang is thrown to one of Big Horn's hands, the hand will display Big Horn's death animation and play the music after a boss is defeated, but Big Horn will still be alive	All
Birthright	Playing as Keeper, having more than 3 HP, and entering the area in which Knife Piece 2 can be acquired will remove the fourth HP (can be increased back to 4 HP after)	All
Birthright	Playing as Magdalene, having more than 12 hearts, and entering the area in which Knife Piece 2 can be acquired will completely remove all hearts above 12.	All
Black Hole	Falling into a Pitfall while the Black Hole is active will result in Isaac becoming headless, immobile and invulnerable, softlocking the run until it is quit and resumed.	All
Black Market	Creating and entering a trapdoor which also leads to a Black Market (for example by We Need To Go Deeper! or an Rune of Ehwaz rune) results in not being able to escape the Black Market other than going to the next floor.	All
Black Market	Using Telepills or Undefined to enter a black market in the mirrored world on Downpour II and Dross II will generate a black market with no items and no exits. Without any other means of teleporting, this will softlock a run.	All
Blanket	Blanket doesn't work in Dogma and The Beast boss fights.	All
Blastocyst	Blastocyst will briefly appear as the largest form before splitting into smaller ones, regardless of which form was killed.	All
Blighted Ovum	The D10 can reroll the Suture half of Blighted Ovum	All
Blood Oath	Using Glowing Hourglass to return to the previous floor twice will cause Blood Oath to activate an extra time, giving buffs corresponding to drained HP.	All
Blood Oath	Upon coming back from obtaining Knife Piece 2 or after defeating the Lamb and refusing a victory lap, the stat boost obtained from this item at the beginning of the floor will be gone.	All
Blue Key	If used with The Forgotten and Birthright, leaving The Forgotten's body in the hallway will cause it to reappear next to you when you exit, but upon switching back to the body, it will become immobile, and switching back to the soul will make it immobile too, causing a softlock requiring you to exit then continue the run.	All
Blue Key	Opening a locked door without entering it and then leaving and re-entering the room will no longer cause the door opened by Blue Key to lead to a Blue Womb room. In other words, this removes the downside of the trinket.	All
Bob's Bladder	Bob's Bladder will not contribute to the Bob transformation despite having the item tag.	All
Bob's Rotten Head	Although Bob's Rotten Head works normally with Butt Bombs and Bomber Boy has no effect with it, their combination drops the explosion damage by 50%.	All
Bomber Boy	Due to the extreme force of multiple simultaneous explosions, it is possible for Bomber Boy bombs (especially when combined with Mr. Mega) to propel Isaac into obstacles or over pits.	All
Bomber Boy	Although Bob's Rotten Head works normally with Butt Bombs, and Bomber Boy has no effect with it, their combination drops the explosion damage by 50%.	All
Bone Spurs	If switching between Tainted Lazarus and Dead Tainted Lazarus with the Flip item, there is a chance to spawn a mass amount of bone spurs on the place you flip each time you use the item.	All
Book of the Dead	If sufficiently many bone orbitals are created, other familiars may disappear. Collecting a new familiar or resuming the run will restore the missing familiars.	All
Book of Virtues	As Tainted Isaac, dropping and picking up the uncombined Book of Virtues will refresh the item's charge, allowing for max wisps.	All
Book of Virtues	Each use of Glowing Hourglass that does not move Isaac to a different room from the one he is currently in (such as by teleporting to the previous room then using it again) will duplicate the wisps. Any extra wisps created from duplication on a filled ring will appear at the entrance of each room Isaac enters and shoot in the direction Isaac is currently shooting.	All
Book of Virtues	Using a Dice Room or being hit as Tainted Eden to reroll an uncombined Book of Virtues will result in it rerolling into a different passive item while still remaining in the active item slot. It will disappear when Isaac picks up a different active item.	All
Boss Rush	It is possible for item pedestals to spawn on red poop (which can be spawned by Carrion Queen or red Dingle) or spikes. Attempting to pick up the item will damage Isaac.	All
Boss Rush	One of the possible layouts for the Boss Rush room will have spikes near the location that an item pedestal spawns after completing the fight. If you possess There's Options, one of the item pedestals can appear in the same place as the spikes, causing you to take damage by picking that item up.	All
Boss Rush	Entering Boss Rush after the 20 minutes (killing Mom before it, but waiting to enter) and using Glowing Hourglass will crash the game.	All
Boss Rush	PS4 Mama Mega! cannot be used to open the door to Boss Rush.	XboxOne
Breath of Life	This item does not work with Broken Remote.	All
Breath of Life	Replacing this item with another active item, switching into another active item with Schoolbag, or directly removing it via debug console while holding the active item key causes Isaac to take damage, even if the charge bar isn't depleted at all.	All
Brimstone	Picking up Brimstone before picking up Scorpio will not change the beam's color. Picking up Scorpio before Brimstone, however, will properly change it to green.	All
Brimstone	When having Brimstone + My Reflection and facing towards an east/west wall, standing directly in front of it will make Isaac shoot in reverse — the front-facing oval Brimstone beam will shoot from the back, and the back-facing beam will shoot from the front.	All
Brimstone	Brimstone will occasionally fire the laser the opposite direction.	PC
Broken Shovel	Taking second part of Mom's Shovel on different Tainted Lazarus form won't assemble the shovel.	All
Brownie	Rarely, Brownie will slide around the room incredibly quickly, resulting in unavoidable damage.	All
Buddy in a Box	The familiar will change upon exiting the Knife Piece 2 area.	All
Bum Friend	If hit by an explosion before finishing collection on the room, Bum Friend may freeze in place.	3DS
Bumbo	Bumbo's level can be reset after the sequence of obtaining Knife Piece 2 in Ashpit/Mines II.	All
Bumbo	Collision between Bumbo and other bum familiars such as Dark Bum can prevent them from collecting pickups if you're holding one of the firing buttons upon entering a room	All
Bursting Sack	Spider enemies that are neutralized by Bursting Sack cannot be poisoned by contact via The Virus, Serpent's Kiss, or turned into gold via Midas' Touch. They also become immune to contact damage from My Little Unicorn, The Gamekid, and The Nail, but not the damage from Midas' Touch or Little Horn.	All
Butt Bombs	Although Bob's Rotten Head works normally with Butt Bombs, and Bomber Boy has no effect with it, their combination drops the explosion damage by 50%.	All
Buttons	In trap rooms with retracting spikes, pressing the plate within five frames of the spikes deploying will cause them to appear to fail to retract, but this is only a visual bug, and they will not deal damage. This can be fixed by leaving the room and re-entering.	All
Buttons	If D12 creates a Reward Plate in the boss room on the floor where an alt door is allowed to appear (After A Secret Exit is unlocked), activating the button to create enemies and kill will create another one, up to 4 doors (depending on the size of the room). Exiting the boss room will leave only the original alt door. By entering a copy of the door, you can go to the alt floor and if you exit, the original door will also be open, even if you did not open it.	All
C Section	There's no idle animation for C Section's costume, so Isaac (and every other character other than Lilith) will always appear to be walking when charging a shot, even when stationary.	All
C Section	Tainted ??? does not have a costume assigned for C Section (despite ??? having one), and nonetheless always appears to be walking while charging a shot, even when stationary (see previous bug).	All
C Section	While Isaac has both C Section and Incubus (including Lilith's inherent Incubus), Incubus' flying animation does not play while not firing; it floats around with no animation at all. The animation plays normally while firing.	All
C.H.A.D.	Using the Emergency Contact on C.H.A.D. then killing him while he is held will crash the game.	All
C.H.A.D.	Killing C.H.A.D. for the first time using Tainted Lost will not unlock Little C.H.A.D.	All
Cain	Cain's covered eye can be seen through the reflection on the floor on stages/rooms with water.	All
Camo Undies	Shooting with mouse control enabled will not break the camouflage effect, permanently causing confusion effect on enemies, but without granting the stat bonuses.	All
Camo Undies	Triggering Dark Arts while Camo Undies are still active will deactivate Camo Undies for the duration of Dark Arts, after which Camo Undies will reactivate.	All
Cantripped!	Receiving the Bag of Crafting as a card and using it will crash the game.	All
Car Battery	Mr. ME!: Grabbed items and pickups may become ghostly and impossible to pick up. Leaving the room and returning fixes this.	All
Card Reading	In the first floor of a Victory Lap, the portals will appear but cannot be entered. It will work again from floor 2.	All
Card Reading	Entering one of the portals causes the Found Soul familiar to become invisible until Isaac drops and picks up the trinket again or enters a new floor.	All
Card Reading	Using a portal, then rewinding time with the Glowing Hourglass will not cause the portals to reappear.	All
Card Reading	Portals may on rare occasion appear in Death Certificate rooms, even under item pedestals. Taking the portal will simply teleport Isaac to another room inside the Death Certificate area.	All
Cards and Runes	{{{description}}}	All
Cards and Runes	Rune of Hagalaz will open Secret Room doors in L-shaped rooms.	All
Cards and Runes	Using XVI - The Tower? in a Boss Room may block all paths to the trap door, resulting in a softlock if no bombs or flight are available.	All
Cards and Runes	Using XVI - The Tower? can also trap certain familiars over the rocks such as Lost Fly until Isaac leaves the room.	All
Cards and Runes	Any blue flies, blue spiders, friendly enemies, locusts, orbital bones, and wisps created by cards, runes, and soul stones can be multiplied when Glowing Hourglass teleports Isaac in a way that does not move him to a different room from the one he is currently in (such as by teleporting to the previous room then using it again).	All
Cards and Runes	As Tainted Lazarus, all effects of XIX - The Sun? except bone heart conversion and sprite change will disappear when flipping.	All
Cards and Runes	Entering the Knife Piece 2 area while under the effects of XIX - The Sun? will cause a visual bug wherein Isaac will revert to his default appearance but still be capable of flight and spectral tears.	All
Cards and Runes	If an activated collectible on a pedestal is touched and then rerolled with Soul of Isaac, the alternate item(s) will also count as "already picked up": they will not drop pickups, grant health or transformations they normally would.	All
Cards and Runes	If multiple Souls of the Forgotten / Jacob & Esau are used in the same room, only 1 Forgotten/Esau will be removed after leaving the room. For every room that is left, one copy of them will disappear.	All
Cards and Runes	Using a Black Rune in a room with exactly one pickup and one item while being near the fly limit won't suck the item.	All
Carrion Queen	Sometimes when entering the boss room and skipping the cut scene, Carrion Queen will spawn in the door, dealing damage to the player.	All
Carrion Queen	While petrified, her entire body can be damaged.	All
Carrion Queen	Each of the three segments of Carrion Queen will drop a heart instead of just one.	All
Carrion Queen	Carrion Queen's last segment can be temporarily disconnected with Anima Sola.	All
Challenge Room	If the game crashes or you close it before you finish the challenge room it will crash every time you try to continue that run.	All
Challenge Room	If Isaac encounters Greed or Super Greed in a Secret Room next to a boss challenge room, the path to the boss challenge room is boarded up from the mini-boss fight. Defeating Greed or Super Greed does not remove the boards, despite the room no longer being active.	All
Chaos Card	If used against Scolex while he's jumping, Chaos Card will not instantly kill him and will instead cut off the bottom of his tail, dealing some damage. Although his weak point will no longer be visible, its hitbox will be and can still be damaged as normal.	All
Chests	If a smaller chest is present in a room, re-entering the room will make the chest appear in a regular size.	All
Chests	Unless the player has enough keys, flight, or any form of teleportation, the Mega Chest can block the way of a narrow passage way and may even deny access to many other rooms such as the Boss Room, possibly softlocking your run.	All
Chimera	Chimera's head will occasionally disappear once the body is killed, rendering them unbeatable unless the player exits the game and continues the run.	All
Chub	If Chub is killed while frozen by Mom's Contacts, only the part to receive the last shot will die.	All
Chub	Chub's last part can be temporarily disconnected with Anima Sola.	All
Clicker	If Lazarus dies, becomes Lazarus Risen, and then uses Clicker to become another character, the character will have Lazarus' hair and freckles. This also works with reviving items such as Ankh.	All
Clicker	If Clicker is used in The Soul form of The Forgotten, it is possible to be turned into another Forgotten. Both Forgottens have independent health bars and can be swapped between, but no Soul form exists anymore. Turning into any other character does not cause the bug.[Check ingame]	All
Clicker	If Clicker turns the player into Jacob and Esau, after collecting Eden's Blessing previously in the run, any items that would have been normally gained at the beginning of the next run, are instead given to Jacob and Esau instantly. This makes it so that no free random items are gained at the start of the next run.	All
Clicker	If Clicker is used as Tainted Lazarus while holding Birthright, the active form will click to another character, but the other form will still be in its ghostly form due to the effects of Birthright. Clearing rooms will alternate between the activity of the ghostly form, switching it's vulnerability and health from the main character, and placing clicker in the pocket item slot. Exiting and re-entering the game during this will cause a softlock unless the player has a second controller, which if not available, will make the player unable to continue the run.	All
Clutch	If a Clickety Clack is killed (e. g. with Euthanasia) just as Clutch decided to swap to it (and before the boss reaches it), Clutch will charge at the bone pile, seemingly trying to posess it. The boss will stay in this state until its health is reduced below 25% or all Clickety Clarks' bone piles are destroyed, including the one the boss is charging at.	All
Co-op	If the co-op player joins using a keyboard, the join button and the fire button must be pressed simultaneously to bring up the special baby menu. It may take several tries, as the timing seems to be almost frame-perfect.	PC
Co-op	Special co-op babies are not accessible normally due to some of the effects being unfinished.	All
Co-op	Each baby with an ID higher than 562 is unable to appear in-game.	All
Compost	When using the item and obtaining an item (cards/pills/items) at the same time it will make the picked-up item disappear.	PC
Conquest	Killing Conquest quickly while his clones are rushing across the screen and leaving one alive will cause the boss music to continue playing until leaving the room.	All
Corpse	D12 still has a small chance to generate trapdoors in Corpse II. These trapdoors will lead Isaac to ???.	All
Crawl Space	If Isaac's hitbox is small enough (by using One Makes You Smaller pills), it's possible to travel through the walls and ceiling to access the Black Market. In the walls are much harder to clip through, but it can still be done with high speed and help of the stairs or flight.	All
Crawl Space	If Isaac uses a XXI - The World? card inside a Black Market and enters it, he will be taken to the crawl space that leads to the Black Market. If he then tries to leave the crawl space from here, he will be spawned back inside it making exiting to the main floor no longer possible. If this is done on the Chest, Dark Room, The Void, or Home floors it will result in a soft lock since Isaac cannot leave through the trap door that usually spawns in the Black Market.	All
Cricket Leg	Each use of Glowing Hourglass that does not move Isaac to a different room from the one he is currently in (such as by teleporting to the previous room then using it again) will duplicate the locusts.	All
Crown Of Light	If Isaac picks up a Bone Heart while the crown is glowing blue and leaves the current room, the crown will continue to glow blue even though the damage boost is inactive due to the Bone Heart container being empty. Taking any damage won't make the crown turn gray until Isaac fills all of his Red Heart containers and leaves the current room to reset the effect.	All
Cube Baby	Pushing Cube Baby directly into a hole in a way that it cannot slide sideways will cause it to shake until it starts to "float" over the hole, acting as if it were on the ground. It returns to normal if it leaves that hole.	All
Cube Baby	If a Cube Baby is picked up by multiple characters using Mom's Bracelet at the same time, it seems that they are all holding one, but trying to throw "them" at the same time will make Cube Baby disappear, only leaving a trail of creep.	All
Cube Baby	If a non-boss enemy dies within 10 ticks (0.33 seconds) after being hit by Cube Baby, it will be frozen regardless of what killed it.	All
Curse Room	Isaac can pass through Curse Room doors without taking damage even when he should. This usually requires 2.0 speed, a long running start and careful positioning to cross the door before its damage effect kicks in, or alternatively several size downs and very careful nudging along the door's edge.	All
Cursed Eye	In Greed mode, taking Red Heart damage while charging will decrease the displayed Devil Room chance on the Found HUD to 0%. It returns to 100% if the button is pressed again.	All
Cursed Penny	The effect can telport Isaac to the tall room with a broken minecart track in Mines/Ashpit II, if the player hasn't pressed all the yellow buttons and doesn't have a way to destroy the wooden door, the player can't do anything rendering the game softlocked	All
Curses	Curse of the Maze can still teleport Isaac to already explored rooms.	All
Custom Challenges	Using "roomfilter" to prevent Treasure Rooms from spawning will still make a Treasure Room spawn in Downpour/Dross 2. This is due of the fact that a Treasure Room must be generated in the mirrored world in order to spawn Knife Piece 1.	All
Custom Challenges	Using the "canshoot" attribute in combination with "secretpath" can lead to a softlock in the Knife Piece 2 area because the player will not be able to shoot along with not having any items from the challenge itself. Often times room layouts will contain a poop that needs to be broken in order to open up a path.	All
Custom Challenges	Angel Rooms can still appear while holding the Book of Virtues, even if they've been disabled with "roomfilter".	All
D10	The D10 can reroll the Suture half of Blighted Ovum.	All
D10	Using this item on any monster with several pieces will reroll every piece into a monster. Mr. Maw and Gemini's cord dots are considered pieces, each turning into a new monster.	All
D10	Rarely, a monster can be rerolled into the mask half of the Mask + Heart enemy, and the mask will die instantly.	All
D10	The Attack Fly, Swarm, and Camillo Jr. enemy can't be rerolled (even though monsters can be rerolled into them).	All
D10	Using this item in a room with Stone Grimaces will turn them invisible. They will not fire, but the space they occupied will prevent Isaac from moving through it like an invisible wall.	All
D10	D10 and items related to it can reroll frozen enemies into alive ones, effectively bringing them back to life.	All
D100	The D100 can reroll Angel Room passive items into the Book of Virtues. Upon further use, the Book of Virtues will not be rerolled.	All
D12	Using D12 while Tainted Forgotten is sitting over a pit (not being thrown) will make his head and weapon disappear, rendering him unable to attack and preventing Tainted Soul from picking him up, unless the room is left or the run is exited and resumed. This can easily cause a soft-lock.	All
D12	If D12 creates a Reward Plate in the boss room on the floor where an alt door is allowed to appear (After A Secret Exit is unlocked), activating the button to create enemies and kill will create another one, up to 4 doors (depending on the size of the room). Exiting the boss room will leave only the original alt door. By entering a copy of the door, you can go to the alt floor and if you exit, the original door will also be open, even if you did not open it.	All
D12	When rerolling obstacles while Isaac has 2Spooky; any Movable TNT or Fire Places spawned in the fear radius has a chance of being spawned momentarily feared with only the purple tint to indicate the status effect. This effect lasts even on the remains of either object after it's destroyed before the fear effect ends. Corn poops created in the radius are unaffected however the Eternal Fly may also become temporarily feared. Venus has the same bug with the only difference being that it is charming obstacles and Eternal Flys and turning them pink	All
D12	If Isaac has Car Battery and uses D12 two times or more in a quick succession (possible with The Battery), some obstacles may become stacked (there will be two or more obstacles in the same spot).	All
D4	Previously held items are not removed from the pause menu, which makes it difficult to determine which items Isaac currently has if they're too many to appear on the HUD.	All
D4	When D4 is used with a co-op baby present, the baby's sprite will turn into a glitched sprite of Isaac.	All
D4	If Isaac rerolls Schoolbag, he will keep both active items, but if he picks up a new active item it will swap with the one currently selected and the other will disappear.	All
D4	When Schoolbag is rerolled away while another active item is held along D4, the other active item will be dropped on a pedestal. Activating D4 after the other active item is dropped will then reroll D4 itself.	All
D4	An item picked up is assigned the pool of the most recently generated item; usually this has correct results but a difference can be seen, for instance, by killing a boss, entering a Devil Deal that has items and collecting the boss reward after seeing the Devil items. The boss item will be rerolled to a Devil pool item with D4. Items with no item pool (starting items, fixed drops etc.) will always use the item pool of the most recently generated item from an item pool as a result; if no items from item pools were encountered yet, the treasure room pool is used.	All
D4	Items that are rerolled are assigned the pool of the item with the highest item ID. This means one reroll with the D4 will probably go as expected, but further rerolls will be proliferated by items from the pool that had the highest ID before the first reroll.	All
D7	If used in a non-Boss Room containing Chubs, C.H.A.D.s, or Carrion Queens, each segment of the boss(es) will be revived as an entire clone, tripling their number.	All
D7	If used in a "trap room" with Grudges after all Pressure Plates were pressed, all Grudges will respawn and will remain active if the room is left and re-entered.	All
Dad's Ring	This item's visual appearance is overridden by some items, rendering the ring invisible. It will still behave as normal in this state.	All
Dad's Ring	When Pause is used with Dad's Ring, it creates a second ring of light that stays in place where Isaac used "Pause" which lasts for the active item's duration. The second ring is a visual glitch and does not interact with enemies. Moreover, both rings are flashing for the duration.	All
Daddy Long Legs	During the mass-stomp attack, the player will take damage before the animation even begins, making it impossible to dodge.	All
Daddy Long Legs	During the mass-stomp attack, if the player deals damage to one of the legs that would normally kill a full health Daddy Long Legs, it will cause the leg to die as a separate Daddy Long Legs. This will not damage the boss at all.	All
Daddy Long Legs	If you freeze one of Daddy Long Legs's legs, then kill Daddy Long Legs while a Spider is still alive, then kill the Spider, the boss fight music won't stop. This is fixed if Isaac leaves the room and then re-enters again.	All
Dark Arts	Using Dark Arts after using Doctor's Remote before the missile hits the ground will trap Isaac in the animation of holding the remote over his head until leaving the room or getting hit, preventing you from firing tears.	All
Dark Arts	If tagged during a dash attack, certain enemies and bosses will "dash" without actually moving after Dark Arts end. This is most notable for The Cage - the boss will roll in place for a couple of seconds. If such an enemy gains momentum in any way (e. g. via collision with other enemies, explosions, or knockback from Isaac's tears), it will resume the dash.	All
Dark Bum	Activating Glowing Hourglass twice after Dark Bum picked up Red Hearts and before he finishes his animation will save his Red Heart pick up progress while the Red Hearts will stay untouched in the room.	All
Dark One	Upon entering the room, if the player goes toward the bottom-center of the screen and The Dark One uses his dashing attack, there is a chance that The Dark One will freeze on his dashing frame and remain in the same state for the remainder of the fight. This bug has been observed when entering from both the left and right sides of the screen.	All
Dead Bird	When using Extension Cord with Dead Bird, if Isaac and the bird are both moving sometimes the electricity does not always fully connect.	All
Dead Cat	If picked up as ???, Dark Judas, Tainted Judas, Tainted ???, Tainted Forgotten, or Tainted Bethany while in possession of Bone Hearts, the health bar may become glitched. The actual health amount is correctly set to 1 Soul Heart/ Black Heart + all Bone Hearts, but some of the Bone Hearts are incorrectly displayed as half Soul Hearts depending on the situation before picking up Dead Cat. This can mess with the order of Soul Hearts and Bone Hearts after taking damage or gaining health. The glitch will resolve itself after taking damage, picking up health or touching an item.	All
Dead Eye	When picking up Brimstone, Technology, Dr. Fetus, Epic Fetus, or Mom's Knife, the damage multiplier that was gained before picking them up will now be permanent. However, saving and quitting the run will result in this damage multiplier being permanently lost.	All
Dead Sea Scrolls	If an effect triggers and adds to the character's appearance while being held (Monstro's Tooth or Kamikaze! for example), the additional visual effects will remain for the rest of the game or until they are replaced.	All
Death	Quitting the game before the death animation is completed does not allow the player to continue the run, but does not add a death on the stats screen.	All
Death (Boss)	Black champion Death's 2nd phase uses his normal (non-champion) appearance instead of his unique champion appearance, unless he takes damage, in which case he turns red permanently (the same shade any enemy turns, briefly, when they take damage). This was fixed in patch V1.7.8a.	All
Death's List	Swarmers will lose the mark and no reward will be granted.	All
Death's List	Multisegmented enemies such as Mr. Maw and Pin may be impossible to kill in the correct order, as each segment is considered a separate entity and are destroyed as the enemy on the whole dies.	All
Death's List	Other multisegmented enemies such as Larry Jr. can have their segments destroyed in a proper order, but the skull marker is displayed on the wrong segment.	All
Debug Console	If a champion is spawned via the "spawn" command, it will have the same amount of health as the non-champion version of that monster, unless the spawned champion variant has decreased amount of health.	All
Debug Console	If the player has debug 10 enabled and starts the sequence to begin the Dogma fight, Dogma will instantly die without continuing the sequence, softlocking Isaac in the room without returning control to the player. This is fixed after exiting and continuing the game.	All
Debug Console	Using the "rewind" command removes all broken hearts on The Soul if there are any.	All
Debug Console	Using the "rewind" command disables all debug flags.	All
Debug Console	Debug Console may rarely break, and will not turn off.	All
Debug Console	Using debug 12 during the Knife Piece 2 sequence in Mines/Ashpit II will crash the game.	All
Deep Pockets	While holding Esau Jr., swapping to the character without Deep Pockets then collecting or spending coins will cap the number of coins at 99.	All
DELETE THIS	Using a 6-Pip Dice Room or D100 or D4 will cause the game to crash while doing this challenge.	Switch
DELETE THIS	Using XVII - The Stars? will cause the game to crash.	PS4
Delirious	If Delirious is used during the Delirium fight and the charmed boss is killed, it will act as if Delirium was killed, but no chest will spawn.	All
Delirious	If a Pink Champion Polycephalus is spawned by the item, one will have the Delirium skin and the other will have the normal Polycephalus skin.	All
Delirious	If Lokii is spawned by the item, one will have the Delirium skin and the other will have the normal Lokii skin.	All
Delirious	If a Pink Champion The Cage is spawned by the item, one will have the Delirium skin and the other will have the normal The Cage skin.	All
Delirious	Using Delirious multiple times rapidly in the same room can crash the game.	All
Delirious	Using Delirious in Boss Rush or Boss Challenge Room can close the exit even if it was finished beforehand, likely softlocking the player.	All
Delirious	Using Delirious can sometimes spawn a boss without its Delirium skin.	All
Delirious	If Delirious is used against Loki in a room layout where a Poky is present, the Poky will not deactivate until the boss and any enemies it spawns die (which may take an extremely long time). If the player has no card, pill, or rune to teleport them out of the room, this is effectively a softlock.	All
Delirious	Using Delirious during Mega Satan or Beast fight can lead to a softlock.	All
Delirious	If a Mega Fatty is spawned by the item during The Beast fight, when the Mega Fatty inhales, it will move the sprites of the bosses in the background.	All
Delirious	If Delirious summons Rag Mega in an uncleared room, the Purple Balls will prevent the room from clearing, effectively causing a lengthy softlock - The friendly Rag Mega does steadily lose health on his own, but this takes a fair while.	All
Delirious	If Delirious spawns Chub, C.H.A.D., or Carrion Queen, only their head will appear.	All
Delirious	If Delirious spawns Brownie, it will sometimes not be replaced if the item is used again, and can only be killed by enemy projectiles.	All
Delirious	If Delirious spawns The Duke of Flies or The Husk, the fly enemies spawned on death will be hostile rather than friendly.	All
Delirium	If Delirium transforms into an enemy like Chub with multiple hitboxes, the game may crash if one of the secondary hitboxes is hit by Chaos Card.	All
Delirium	Delirium can transform into Fallen Uriel, Fallen Gabriel, Bumbino, and The Pile, but they do not have unique Delirium skins.	All
Delirium	If Delirium transforms into Mega Satan, the sprites will bug out. It can attack normally, but the sprite may not be visible/half-visible/only showing the hands.	All
Delirium	On Isaac's last will, Delirium will be shown in its current form rather than its main one. Sometimes it will show his main form, even if Isaac is killed by a different form.	All
Delirium	Delirium can sometimes deal unavoidable damage. For example, when transformed into Mom, the Boss will constantly target Isaac until it stomps down. If Delirium changes during this targeting phase, it can teleport into Isaac, instantly damaging him.	All
Delirium	Sometimes, when Delirium transforms into a segmented boss, its health will appear to be lower than it is. This is usually purely visual and returns to normal whenever it transforms again.	All
Delirium	If Delirium transforms into Blue Champion Larry Jr. it will, due to how Blue Champion Larry Jr.'s HP works, effectively lose a large portion of HP as its total HP will get divided into however many segments it transforms into. It will not receive the lost HP back after transforming again.	All
Delirium	If Delirious is used to spawn Hush, Delirium will be able to transform into Hush.	All
Delirium	If Delirium transforms into Gemini, Suture will stay in its enraged form separated from Contusion when Delirium transforms again.	All
Delirium	If Delirium transforms into Blighted Ovum, Suture will keep its usual sprite instead of using its special sprite for Delirium.	All
Delirium	If Delirium transforms into the Mask Of Infamy, it will only transform into the heart.	All
Delirium	If Delirium transforms into The Frail, it will always transform into the first phase, regardless of how much hp it has left (unless it's the Black Champion version).	All
Delirium	If Delirium transforms into Lokii, it will only transform into one Lokii half.	All
Delirium	If Delirium transforms into War's second phase, the body will be invisible (except for when it does its sobbing animation) This also applies to Blighted Ovum's Contusion.	All
Delirium	As of patch V1.7.8, if Delirium transforms into a champion boss, it will retain its normal appearance and color, but its attacks (and size in the case of some forms) will be those of the champion.	All
Dice Bag	Jacob and Esau: Regardless of who is holding the die, it is activated by pressing the consumable key. If Esau is holding an active item, it will be used at the same time as the die. Possibly unintended behavior.	All
Dice Room	The 1-pip room may reroll your active item into a "passive" item. The 1-pip room always empties your active item slot. However 1-pip room may fail to find a replacement item which results in Isaac still having the collectible. This is because the D4 will try 3 times to get a non-active item from the item pool before giving up replacing the item.	All
Dice Room	The 1-pip room will reroll your secondary active collectible without emptying the slot. This means you will keep the active ability but lose some passive abilities. For example, you will lose Mom's Box passive of doubling trinkets but you keep the speed boost from A Pony.	All
Dirty Mind	Each use of Glowing Hourglass that does not move Isaac to a different room from the one he is currently in (such as by teleporting to the previous room then using it again) will duplicate Dip Familiars.	All
Dogma	If the player dies at the same time as killing Dogma's second phase and has extra lives that make him respawn outside of the room, the fight will reset to the start when entering the room again. The static transitioning effect that starts at the end of the fight will remain on the screen after reviving, making it very difficult to see anything during the rematch.	All
Donation Machine	If Isaac donates to the machine, leaves the room, and the game is then restarted using the PS button, the machine will retain its donation and Isaac will have the same amount of coins as he started the current floor with.	Vita
Dople	Maximum mirroring tear rate of a Dople is 15. From 15 to 30 they will fire slower like from 15 to 0 and above 30 they will only fire one tear.	All
Dr. Fetus	The black ring generated from the synergy of Dr. Fetus and Tech X behaves as a Maw Of The Void ring and may cause Black Hearts to drop.	All
Dr. Fetus	Even though having spectral tears will make bombs not collide with obstacles, if Isaac shoots a bomb while on top of an obstacle, the bomb will collide with it, making it possible to take damage.	All
Dream Catcher	Dream Catcher will not show the correct items in Greed Mode.	All
Dream Catcher	Using Glowing Hourglass to go back to the previous floor will keep the soul heart that was obtained from Dream Catcher.	All
Dream Catcher	Wrong items are shown when combined with Broken Glasses unless More Options is acquired.	All
Dull Razor	Habit will charge Dull Razor if Isaac has The Battery.	All
E. Coli	Effects like Monstro's Tooth and II - The High Priestess can target poops created by the item.	All
Eden's Blessing	A bug may occur when the item is picked up, and Glowing Hourglass is used with either ? Card or The Battery to reverse time, out of the room, restoring your ability to get out using either of the two items and the Eden's Blessing pickup. This will allow you to generate an endless amount of Eden's Blessings, which will all carry over to your next run, and may be repeated endlessly.	All
Eden's Blessing	If Clicker turns the player into Jacob and Esau after collecting Eden's Blessing, any items that would have been normally gained at the beginning of the next run are instead given to Jacob and Esau.	All
Eden's Blessing	If the game crashes on the floor where you have taken Eden's Blessing (like during a breaking run), that counts as +1 item for the next run. If you continue the saved game and you take Eden's Blessing again, you gain an additional +1 item for that run. This process can grant you unlimited items for the next run.	All
Empty Heart	If Isaac is operating only on soul hearts and manages to get 12 empty heart containers by using this item, he will die immediately upon leaving the spawn room or picking up an item.	All
Empty Heart	Using Glowing Hourglass to go back to the previous floor will keep the new empty hearts that was obtained from Empty Heart.	All
Eraser	If used to kill Dogma or the Mom's Heart leading to Corpse, it will not count it as a kill, preventing progress on the respective paths.	All
Esau Jr.	If one character has Deep Pockets, swapping to the other character then collecting or spending coins will cap the number of coins at 99.	All
Esau Jr.	Upon swapping to a character with Bone Hearts for the first time, bone hearts become half soul hearts. This is only cosmetic, and they become normal again if health is updated (obtaining HP up items, etc). The bone hearts must be obtained before the first swap to cause the bug.	All
Esau Jr.	If at least one character has Spear Of Destiny or Trinity Shield, swapping to the other character causes these items to leave a stationary copy of themselves until Isaac leaves the room. The stationary spear is only a visual bug with no collision while the stationary shield still blocks tears.	All
Explosivo	If an explosive tear sticks to a Nulls or a Begotten, when they become invisible, the tear will fall to the ground.	All
Extension Cord	When using BBF, electricity will arc to its last location before exploding, until it respawns.	All
Extension Cord	When Holy Water breaks, the sprite is temporarily stored just off the top-left of the screen, toward which electricity will still arc.	All
Extension Cord	During the Siren fight in mausoleum if she converts any familiars Isaac will take constant damage.	All
Eye of the Occult	After the first Brimstone shot, the Twisted Pair familiars will be unable to fire until Isaac moves the crosshair and even then they will often only fire once or not at all. Chocolate Milk fixes this.	All
Familiar	Exiting the game and re-entering will cause all Blue Spiders to disappear.	3DS
Famine	If phase 2 of Famine is inflicted with fear or confusion, instead of running away from Isaac, it will chase him without attacking.	All
Famine	If Famine is stunned at the same time as he tries to shoot Isaac after the effect wears off, his shots will be fired without his corresponding animation.	All
Finger!	The floating finger familiar is not reflected properly on Chapter 1.5 or other rooms that have water.	All
Fire Mind	Fires spawned by Angelic Prism will damage Isaac.	All
Flush!	Flush! works against Lil Haunts but it can softlock the game.	All
Forget Me Now	The new floor is improperly seeded. This results in a high chance for rooms to repeat from the previous floor. This is most noticeable when looping via the error room. This bug is due to ForgetStageSeed using the same xorshift constants as the level generator.	All
Found Soul	Resuming a Jacob and Esau run with Found Soul equipped in Esau's trinket slot will require a controller to continue. If a controller is available and plugged in, Found Soul can be controlled like a Co-op baby and won't mimic either brother's movements. This effect won't happen if Jacob holds the trinket. If no controller is available, the run is softlocked and cannot be continued.	All
Found Soul	When used together with Azazel's Stump, the soul familiar sometimes keeps Azazel's properties (flight and short brimstone) for a few rooms after Isaac has transformed back to normal. Lil Clot also has this bug.	All
Found Soul	If Sulfur has been used in a room before picking up Found Soul, it will retain Brimstone until dropped/killed, even through rooms.	All
Found Soul	Entering one of the portals created by Card Reading, Lil Portal, and Ventricle Razor causes the familiar to become invisible until Isaac drops and picks up the trinket again. Entering a new floor sometimes also causes this bug.	All
Found Soul	It is possible for both Isaac and the soul to target the same enemy/boss with Suplex! (easier to do on enemies with large hitboxes such as Hush). In this case, the enemy/boss may become invulnerable and/or invisible after the slam. Dropping the trinket or having the soul die does not fix the situation.	All
Found Soul	If Isaac's items are rerolled (via D4 or similar effects) while Found Soul is held, the soul will look like Isaac's detached head or his headless body. Dropping the trinket and picking it up again returns the soul its normal appearance.	All
Freezer Baby	If a non-boss enemy dies within 10 ticks (0.33 seconds) after being hit by a freezing tear, it will be frozen regardless of what killed it.	All
Friendly Ball	Certain monsters will not spawn friendly enemies when defeated: Moter Swinger Dinga Black Globin's Body	All
Gaper	If a Dark-Red champion Frowning Gaper does not become a Pacer or Gusher and regenerates, the head won't appear until it sees Isaac. The same goes for a Gaper, however the head won't appear at all.	All
Gaper	If an Explosivo tear is stuck to a Nulls when it becomes invisible, the tear will fall to the ground.	All
Gaper	The Explosivo tear will instakill a Nulls when it becomes invisible.	All
Gaper	If a Champion Gaper is killed and it turns into a Pacer or Gusher, it will no longer be a champion.	All
Gaper	Cyclopias become unable to shoot while slowed, either through attacks that cause the slow status or global effects like Stop Watch.	All
Gello	Using ? Card on Gello will still result in the charges being used once Gello is whipped out. The ? Card will be used up as well, despite providing no free use of the item.	All
Gemini	Gemini's cord dots are considered monsters, and each one will turn into a new monster if the D10 is used in the room.	All
Gemini	To unlock Cellar, Isaac must kill all Basement bosses once. Gemini, however, counts as two depending on which part is killed first.	All
Gemini	If you Stun Suture at the same time that it tries to shoot Isaac, it will cause the sound effect to loop infinitely until Suture is killed.	All
Gemini	If Gemini's chain hits Red Poop or Spikes, the chain will disappear but Contusion and Suture will still be joined.	All
Genesis	Using Genesis immediately after taking Dad's Note will teleport Isaac to the Genesis room, then to the start of the ascent with no items except those that cannot be removed (Dad's Note, Key Pieces, etc.).	All
Genesis	Genesis removes wisps created by Lemegeton but not the item effects associated with them. These remain permanently active until Lemegeton is used again.	All
Gilded Key	Picking up a golden Gilded Key does not give a key.	All
Glass Cannon	Glass Cannon can be used to steal Devil Room items by using it to set your health to half of a Soul Heart or no health at all before you die. In the latter case, picking up any item that isn't a health upgrade will kill Isaac.	All
Glass Cannon	If Tainted Forgotten takes damage with the cannon held above his head, he will be unable to fire and unable to attack. Exiting and continuing will fix this.	All
Glitched Crown	Glitched Crown still attempts to create 4 extra items when a quest item is generated (such as Key Piece 1), but because quest items cannot be rerolled, it will delete 4 items from that room's item pool.	All
Glitter Bombs	The limit of generated pickups is reset when exiting and reentering the game.	All
Glowing Hourglass	For some reason, having Error trinket with you will make your familiars "respawn" each time you use Glowing Hourglass, which leads for some interesting interactions. For example, Buddy in a Box and 7 Seals will change their forms each time leap, and the Star of Bethlehem will change its position to the room where you ended up after the time leap, allowing you to move it where you want it to be.	All
Glowing Hourglass	Going back in time will add one more copy of each familiar that were created by Monster Manual for the duration of the room you ended up in, regardless if you have it with you or not. Exiting this room and using Glowing Hourglass again will add another copy for each time leap you do, it will still last untill you will exit that room and will be reset afterwards.	All
Glowing Hourglass	Going back to the starting room will undo some map-revealing effects, such as The Compass.	All
Glowing Hourglass	If a new game is started and Eden begins with this item, using it in the first room will remove Eden's starting items.	All
Glowing Hourglass	Using the reworked Glowing Hourglass in the starting room in Greed mode or Greedier mode will result in a game crash.	All
Gnawed Leaf	Leaving and re-entering a run while in statue form makes Isaac continue to appear in statue form, though he is vulnerable.	All
Gnawed Leaf	Moving as Tainted Forgotten doesn't disable Gnawed Leaf. (Attacking however, does)	All
Golden Trinket	Golden trinkets rerolled by D20 will cause the resulting pickup to have the golden effect applied to it. If this is a trinket, the trinket will turn into a standard trinket, otherwise the gold effect will do nothing and will disappear upon leaving and re-entering the room. Additionally, items spawned by chests with the gold effect applied will be golden as well, however other pickups dropped by chests will not be.	All
Great Gideon	Spawning Great Gideon with the debug console will spawn him with a normal boss healthbar instead of a "waves" mechanic. When Great Gideon attempts to spawn a wave of enemies, the game crashes.	All
Great Gideon	Dealing enough damage quickly enough (e.g. with Soy Milk) to the monsters Great Gideon creates can cause him to spawn the next wave before all enemies in the current one are dead.	All
Greed Mode	If the Super Secret Room is generated behind the locked (golden) Treasure Room, it is possible to get stuck by teleporting into before unlocking the Treasure Room. The Treasure Room doors all become unlocked when one of them is, unlike the normal game mode where a Treasure Room may have only one locked door, which results in the bombable wall between the Super Secret Room and the Treasure Room also being "locked". It cannot be bombed or opened with a key from inside the Super Secret Room, and unless another means of teleporting is available, the run is softlocked.	All
Greed Mode	Using Genesis forces you down a new "Ultra Greed" floor instead of the safe place, even if the final boss is already killed.	All
Greed Mode	Dream Catcher shows the wrong items in Greed mode.	All
Greed's Gullet	For the Keeper characters, they gain an additional Coin heart container slot, separately from the HP gaining increments, which they can fill by getting HP ups. You gain one of these every 25 coins even with Deep pockets. You can gain an additional 39 via this bug.	All
Grub	Attempting to capture a Grub with Friendly Ball will only capture one segment of the Grub.	All
Guppy's Collar	When the Keeper is resurrected by Guppy's Collar, there is a chance he spawns with a Half Soul Heart instead of Coin Hearts. When an HP up is obtained, Keeper will have 1 Coin Heart, as well as the Half Soul Heart he had previously. When a second HP up is obtained, Keeper will lose the Half Soul Heart and have 2 Coin Hearts, like normal.	All
Guppy's Collar	Guppy's Collar can be exploited to gain infinite lives. When Isaac's last will is on the screen, close the game, re-open it, and continue the run. Isaac will appear to die again, and will also have a separate chance to be resurrected.	All
Guppy's Hairball	Killing the Hush Flies that Hush spawns does not increase the hairball's level.	All
Guppy's Paw	If Keeper uses Guppy's Paw to remove all his Coin Hearts, he will not die until he picks up an item.	All
Gurdy	Using A Card Against Humanity will cause Gurdy to appear to teleport onto the player. This is purely a cosmetic effect and clearing the poop from the center of the room will cause her to return to normal.	All
Gurglings	If the player stays close to walls, the Gurglings will not charge.	All
Gurglings	If both Gurglings charge at once, only one of the Gurgling's grunting noise file will play.	All
Gurglings	When fought in the Boss Challenge Room, they will appear in their enemy form rather than their boss form, making them much weaker and lacking a health bar.	All
Gurglings	When the Gurglings are slowed and attempt to charge Isaac, they can't move and constantly spawn Attack Flies. Similarly, the "mini-boss" Gurglings attempting the same attack will constantly shoot 6 blood tears.	All
Haemolacria	When using The Forgotten's melee attack with both Jacob's Ladder and Haemolacria, the sparks caused by splattered tears will hurt the player. (Video clip)	All
Haemolacria	Using Mom's Knife and Marked with Haemolacria will cause it to only fire towards the center of the room; using the fire buttons will barely move the Marked icon, while Mom's Knife will be unusable and locked to the right.	All
Health	A Gold Heart surrounding a Soul, Black, or empty Bone Heart will be used if a Red Heart is depleted via the alternate order before the rightmost heart is lost.	All
Health	Losing many hearts at once, such as via Dead Cat or a Hematemesis pill, while having a Gold Heart will trigger the Gold Heart loss effect many times at once, showering the player in coins.	All
Health	If the last Rotten Heart is drained when Isaac has an Eternal Heart, the latter will turn into a Half Red Heart. The same will occur if normal damage is taken to a Rotten Heart while Isaac has an Eternal Heart. If in this scenario the Rotten Heart fills the Bone Heart, the Bone Heart will be filled with a Half Red Heart after taking damage even if a full heart worth of damage is taken.	All
Hearts	Gold Hearts actually simply compare Isaac's current heart count to what he had on the previous frame, leading to two bugs. Firstly, it's possible for a Gold Heart to burst when health other than the rightmost heart is lost, such as using up Red Hearts with a Blood Donation Machine. Secondly, the "previous frame hearts" value is updated incorrectly; a Gold Heart bursts immediately upon pickup if Isaac had and lost a Gold Heart earlier, and his current heart count is lower than after losing the previous one.	All
Holy Mantle	If the Holy Mantle is removed from Isaac's inventory — for example, when using the D4 — Isaac can still take one damage and it will be negated with Holy Mantle's effect, but only in the room where the items were re-rolled.[Check ingame]	All
Holy Mantle	Activating Soul of Judas at the same time Isaac blocks a hit with Holy Mantle, time will freeze as normal, but Isaac will be allowed to shoot during the duration of the Dark Arts effect.	All
Holy Mantle	Upon leaving the game and reentering it, if Holy Mantle was broken in the room, it will be restored.	All
Holy Water	If Isaac has the Extension Cord and Holy Water breaks, the sprite is temporarily stored just off the top-left of the screen, where the yellow beams will still connect to it.	All
Home	If the player uses Delirious during The Beast fight, and it summons Rag Man during The Ultra Harbingers phase, the battle will softlock or crash due to the dead Rag Man's Raglings counting as enemies	All
Homunculus	If an Explosivo tear is stuck to a Begotten, when it becomes invisible, the tear will fall to the ground.	All
Homunculus	In the "RoomEditor" modding tool, Homunculi cannot be placed.	All
Horf	If a Horf or Psychic Horf is stunned, feared, or frozen at the same time that it tries to shoot Isaac after the effect wears off, its shot will be fired without its corresponding animation.	All
Hornfel	If Hornfel is killed off screen, the game crashes.	All
Host	If Hosts or Mobile Hosts are affected by fear, shrink, or stunned, then if the effect wears off at the same time as they try to attack you, they sometimes attack without the corresponding animation.	All
Host	Little Horn effect cannot be triggered on Mobile Hosts.	All
Host	If two Mobile Hosts are affected by permenant Charm (on the C0CKFGHT seed), they do not become vulnerable when touching eachother, meaning they cannot attack eachother or be damaged by isaac, softlocking the game	All
Hush	If Delirious is used in phase 2 of the Hush fight and Delirium is killed, The Calm (music usually played after defeating a boss) will replace Morituros.	All
Hush	Having the No Return seed enabled when going to Hush will result in no doors being available, softlocking the run.	All
Hush	Stop Watch / Broken Watch / Using the I'm Drowsy... pill makes the lasers from Hush's eyes late in the fight impossible to avoid, because their speed is calculated based on Isaac's base speed, not accounting for Isaac's slowing effect.	All
Hush	If Hush takes too much knockback too quickly (e.g. from Knockout Drops), the Hush Flies it spawns may teleport around the room erratically, occasionally resulting in unavoidable damage.	All
I AM ERROR	If isaac enters an I AM ERROR room in the first room of the first floor (possible with Eden), and have not entered any rooms yet, using Glowing Hourglass will send him back to an identical starting room, with all of his starting items missing, including the Glowing Hourglass. This also affects items gained from Eden's Blessing.	All
Isaac (Boss)	The Angelic Babies always spawn in the bottom center of the room at the same position.	All
Isaac's Awakening	If you enter boss rush with a respawn with the Knife Pieces already used on the door to Mom's Heart, if you then die in Boss Rush, you will be teleported to the Mom fight with no knife and with the door sealed.	All
Isaac's Awakening	If you teleport into the I AM ERROR room, after using the trapdoor, you will be put back on the regular completion path. If this happens after Mines / Ashpit II, you will be unable to continue on the alt path. Upon entering Womb / Utero / Scarred Womb I, no trapdoor will spawn after defeating the boss of the floor, soft locking the player unless another error room is accessed. After defeating the It Lives boss, a trophy will spawn allowing the challenge to be completed.	All
Isaac's Awakening	If you enter to a Crawl Space that leads to a Black Market while running from Mother's Shadow, and you use the trapdoor, you will be put back on the regular completion path too.	All
Isaac's Heart	When picked up by Tainted Lazarus after picking up Birthright, the character which has Isaac's Heart can be damaged even in ghost form.	All
Isaac's Tears	With Brimstone and Chocolate Milk, the attack can be charged past the fully charged point, firing massive, extremely damaging tears when Isaac's Tears is used.	All
Isaac's Tears	When Isaac's Tears is in the first active item slot of Schoolbag, the secondary item does not charge upon clearing rooms.	All
It Lives	Sometimes, if the boss intro is skipped, the game will not teleport Isaac into the center of the bottom of the room, resulting in immediate contact damage with one of the Eyes or It Lives, depending on the direction of the room's entrance.	All
Item Tags battery	Neither AAA Battery nor Watch Battery will not contribute to unlocking Jumper Cables despite having the item tag.	All
Item Tags bob	Bob's Bladder will not contribute to the Bob transformation despite having the item tag.	All
Item Tags mom	"Mom" trinkets will not contribute to the Yes Mother? transformation nor unlocking Mom's Contacts despite having the item tag.	All
Jacob & Esau	Resuming a Jacob and Esau run with Found Soul equipped in Esau's trinket slot will require a controller to continue. If a controller is available and plugged in, Found Soul can be controlled like a Co-op baby and won't mimic either brother's movements. This effect won't happen if Jacob holds the trinket. If no controller is available, the run is softlocked and cannot be continued.	All
Jacob's Ladder	When using The Forgotten's melee attack with both Jacob's Ladder and Haemolacria, the sparks caused by splattered tears will hurt the player. This does not apply to other tear scattering items.	All
Jar of Flies	The synergy of The Ludovico Technique with Brimstone or Technology will not spawn flies.	All
Jar of Wisps	Each use of Glowing Hourglass that does not move Isaac to a different room from the one he is currently in (such as by teleporting to the previous room then using it again) will duplicate the wisps. Any extra wisps created from duplication on a filled ring will appear at the entrance of each room Isaac enters and shoot in the direction Isaac is currently shooting.	All
Keeper	Guppy's Collar respawns Keeper with half a soul heart	All
Keeper's Box	Keeper's Box can spawn hearts for sale when playing as Keeper/ Tainted Keeper.	All
Key Bum	If Credit Card is used in a Shop with Keys, Key Bum will not be able to pick up the free keys. This can be fixed if Isaac leaves and re-enters the shop.	All
Key Bum	Charged Keys do not increment Key Bum's key count when picked up.	All
Keys	Charged Keys do not increment Key Bum's key count when picked up.	All
Kidney Stone	If Kidney Stone activates while a charged tear effect such as Tech X or Chocolate Milk is currently charging, the charge will get stuck, unable to fire for a somewhat-short period of time, before eventually having the Kidney stone be released as normal. Tears will then occasionally charge, even if a fire button isn't held down anymore.	All
Kidney Stone	With Monstro's Lung and Technology, the stone can be launched but the barrage will not charge Monstro's Lung enough to fire, preventing Isaac from firing at all during the barrage.	All
Knight	The hitbox of Dark Red Champion Knights (and their variants) do not change when they crumble into goo, and they must be shot from the back to damage them.	All
Lachryphagy	In the battle with The Beast and the Ultra Harbingers, outputting high amounts of Lachryphagy tears can cause the damage from all the tears offscreen to be instantly applied to each entity the moment they arrive to fight Isaac.	All
Lachryphagy	Rubber Cement causes all tears on screen to have their damage applied to any enemy that gets hit by a tear.	All
Lazarus	Lazarus will receive a copy of Anemic when resurrecting. The item does nothing when stacked.	All
Leech	Tends to get confused when attacking Maggot like enemies and just moves around in the attacking animation without attacking anything until the Maggot is killed by The Player.	All
Leech	The Leech will continuously heal the player while it's attacking Mama Gurdy.	All
Lemegeton	After using Genesis, Isaac keeps the passive effects of each wisp until the next use of Lemegeton, which erases all lingering wisp effects.	All
Lemegeton	If a run is exited and resumed while Isaac has item wisps generated from Lemegeton, all wisps will be condensed into the middle clockwise ring, even if this would result in more wisps on that ring than normally allowed. This also allows further wisps to be generated on the inner and outer rings.	All
Lemegeton	Each use of Glowing Hourglass that does not move Isaac to a different room from the one he is currently in (such as by teleporting to the previous room then using it again) will duplicate the wisps. Creating wisps in this way allows Isaac to exceed the item's wisp limit.	All
Lil Clot	When used together with Azazel's Stump, the blood clot familiar sometimes keeps Azazel's properties (flight and short brimstone) for a few rooms after transforming back from Azazel.	All
Lil Clot	If Isaac has both The Ladder and a form of flight, the clot familiar will be unable to path over any terrain with a ladder on it despite having the ability to fly, resulting in movement desync.	PC
Lil Delirium	When entering a new floor or room, Lil Delirium and a normal familiar you have can swap forms as long as Lil Delirium is currently transformed as that familiar. For example, if you have Lil Brimstone and Lil Delirium, Lil Brimstone will become Lil Delirium's form, while Lil Delirium will look normal. This persists for the other familiar, but Lil Delirium will go back to normal. This also works if you pick up the familiar Lil Delirium is transformed as.[Check ingame]	All
Lil Portal	If a portal is reencountered during the ascent, such as in a previously completed boss room, the game may crash if the destination the portal originally connected to no longer exists in the now altered floor layout.	All
Lil Portal	A portal can be created next to a door which can block off an entire section of the map and cause a soft lock.	All
Lil Portal	Entering one of the portals causes the Found Soul familiar to become invisible until Isaac drops and picks up the trinket again or enters a new floor.	All
Lil Portal	Activating Glowing Hourglass twice after Lil Portal consumed the last forth pickup will make him drop a portal while the pickups will stay untouched in the room. If you wont move after a second Glowing Hourglass activation Lil Portal will drop a portal right at the entrance, which will block it and may cause a softlock.	All
Lil Portal	If a portal is created during The Beast fight, this can cause a softlock.	All
Little Baggy	Patch V1.7.5 stated that "Little Baggy no longer affects pocket items that are neither pills nor cards (such as runes)", even though that is not the case.	All
Little Horn	Using Spider Mod will display health bars for the Pitfalls Isaac can fall into.	All
Little Horn (Item)	The item's effect cannot be triggered on Mobile Hosts while they walk.	All
Lost Soul	If Lost Soul is killed before the segment with Mother's Shadow, it will respawn after Isaac returns to the normal floor.	All
Lost Soul	Swapping Lost Soul for another item as Tainted Isaac and picking it back up again will cause it to respawn if it died previously. This can also be accomplished with Butter!.	All
Lump	If you stun a Lump at the same time that it burrows underground, it will cause their sound effect to repeat continuously for a few seconds.	All
Lump	If a Lump spawns as a Light White Champion, when the Lump burrows underground, its Eternal Fly will rapidly teleport around the room, potentially resulting in unavoidable damage.	All
Machines	In the Booster Pack 5 update, the Fortune Telling Machine's fortunes are broken and display as a garbled mess.	Switch
Magdalene	There are some stray pixels on Maggy's "Bad Pill" animation.	All
Maggy's Faith	When held as Keeper, blue flies will not be spawned instead of the eternal heart, making the trinket useless.	All
Mama Mega!	Mama Mega! can break the door to the Knife Piece 2 room. If Isaac leaves this room before the intro animation of Mother's Shadow finishes and then enters it again, another Mother's Shadow will be generated.	All
Mama Mega!	PS4 Mama Mega! cannot be used to open the doors to Boss Rush / ???.	XboxOne
Marked	Mom's Knife + Haemolacria: Causes the crosshair to follow the camera instead of player input. In normal rooms this makes the crosshair get stuck in the middle. In larger rooms, the marker will only move when the camera moves, allowing for minimal control when aiming due to how the camera moves based on the direction Isaac is currently aiming.	All
Mausoleum	If the LABY RNTH (permanent curse of the labyrinth) special seed is being used, the door to the mausoleum in Mines/Ashpit generates very infrequently.	All
Maw	If you slow, stun or fear a Maw at the same time that it tries to shoot Isaac, its sound effect will loop infinitely until the Maw is killed.	All
Maw Of The Void	When combined with Chocolate Milk, Cursed Eye, Monstro's Lung or Tech X, releasing a Maw Of The Void attack may prevent a charged shot from firing at the same time as expected. The charged shot is delayed by about ~0.5 seconds. Holding a full charge for a longer time makes the delay more likely to happen.	All
Meat Cleaver	If used on Reap Creep, during his 3rd Phase, he cannot properly collide with the walls in order to perform his rock attack and will infinitely run against the wall.	All
Meat Cleaver	If used against Mom's foot, both will count as their own instance, and the second foot will only be able to be killed once the first one is dead. If the first foot is killed instantly, the second foot may never drop, requiring a reset.	All
Meat Cleaver	If used during Min-Min's phase change, both bosses will be unable to be damaged.	All
Meat Cleaver	If used on The Stain, the boss will be back to normal size when poking out of the ground. This is most likely due to the boss becoming smaller when going underground and therefore overriding the size it was given by the Meat Cleaver.	All
Mega Blast	Quitting a run and resuming it while Mega Blast was active will retain the costume and animation of Mega Blast until the item is used again, but no laser will appear.	All
Mega Blast	If the Glowing Hourglass is used while in the room Mega Blast was used in, the Mega Blast laser will still remain, but the animation will be removed, and a full charge for Mega Blast will be reobtained.	All
Mega Mush	Activating Mega Mush before entering the Knife Piece 2 area will keep the effect active inside the chase area but Isaac will have his normal sized, followed with a huge shadow and will continuously stomp the ground, breaking everything in his way, even pushing away Mother's Shadow.	All
Mega Mush	If Isaac walks over a Teleport Pitfall while Mega Mush is active a visual bug will occur where the pitfall is destroyed and can no longer harm Isaac however its sprites still remain in the room. When Isaac reenters the room or exits and continues the run, the teleport pitfall works normally again.	All
Mega Mush	Using Mega Mush in combination with Suplex! makes you grab enemies and move them around until you leave the room. Doing this on any of the Ultra Harbingers or The Beast will make the enemy disappear and render you unable to move at all.	All
Mega Mush	Activating Mega Mush through Void will cause Isaac to visually revert to normal after leaving the room while still under the item's effects. If Isaac does not have flight, a stomping sound will play and the screen will shake constantly even if he is not moving.	All
Mega Mush	When Mega Mush times out and Isaac returns to normal size, he may occasionally appear to have no head. Isaac is unable to fire tears in this form and cannot interact with enemies or objects or pick up items. He also cannot interact with trap doors or Crawl Space entrances, causing softlocks. Going into an animation (e. g. by taking damage, using a pill, etc.), or exiting and continuing the run fixes this issue.	All
Mega Satan	Doing too much damage between phases will cause the game to play the normal "boss defeated" music throughout the rest of the fight.	All
Mega Satan	If a Pickup spawns under Mega Satan's hand, the hand will start to move and rotate for the rest of the fight until it's pushed away. This is a purely cosmetic bug.	All
Mega Satan	Using Delirious in Mega Satan's fight (after stepping on the pentagram), if Mama Gurdy is spawned, Mama Gurdy will be spawned behind Mega Satan, but it will be able to attack.	All
Mega Satan	If Isaac has Mom's Box and Tick, Mega Satan will start the fight at 70% health, instantly starting the fight at the first wave of bosses. Afterwards, Mega Satan will be invisible the entire fight, and if Isaac moves to the upper half of the arena before Mega Satan dies, the game will softlock.	All
Member Card	Using XVI - The Tower? in the underground Shop can spawn rocks under the ladder, resulting in a softlock if Isaac can't fly or doesn't have any bombs.	All
Member Card	Using IV - The Emperor? in the underground Shop on Mausoleum II, and getting Rotgut as the boss, will result in an infinite loop of entering and exiting the boss room and the shop, respectively.	All
Member Card	On Downpour II (or one of its alternate versions) : Don't go into the underground shop. Go in the mirror world, enter the underground shop's alternate mirror version. It should have nothing for sale. Make the game refill shop. For example by using a restock machine. Go to the regular underground shop in the normal non-mirror world. Now the underground shop contains two overlapped sets of things on sale : One from when the mirror version was restocked, and one from when you entered the "real" underground shop for the first time.	All
Member Card	While playing as Tainted Lazarus : Enter the trapdoor created by Member Card. Teleport to I AM ERROR, for example using Undefined. Use Flip to swap to the other form of Tained Lazarus. Spawn and enter a Crawl Space, Isaac will spawn in the center of the room. Upon exiting the crawl space Isaac will be placed in the Member Card shop, but will be softlocked as the exit ladder will now place him back in the Member Card shop.	All
Metronome	It is possible for this item to give an indefinite Breath of Life effect that persists throughout rooms, eventually killing the player.	PC
Metronome	If Urn of Souls is activated through Metronome, it won't shoot fire and Isaac could get stuck with the urn in his hands unable to shoot tears. You can fix this by exiting and continuing the run, restarting the room without the urn and without Metronome charges.	PC
Milk!	When the milk is spilled and becomes a puddle while Extension Cord is equipped, the electricity will fire consistently to the upper left even when the puddle disappears.	All
Milk!	The milk familiar has a chance to block a projectile, but not count towards breaking.	All
Mine Crafter	Using this item during the Mega Satan fight will cause a soft lock since an exploded barrel counts as an enemy that needs to be defeated before the fight can continue.	All
Mine Crafter	Placing the TNT under the effects of Venus or 2Spooky will tint it as if it were applied the corresponding status effect. It is purely visual and will fade after a while.	All
Mine Crafter/zh	Using this item during the Mega Satan fight will cause a soft lock since an exploded barrel counts as an enemy that needs to be defeated before the fight can continue.	All
Mine Crafter/zh	Placing the TNT under the effects of Venus or 2Spooky will tint it as if it were applied the corresponding status effect. It is purely visual and will fade after a while.	All
Mirrored World	Spawning items with a Restock Machine in a Member Card mirrored shop will result in them overlapping with the items in the non-mirrored Member Card shop.	All
Missing No.	Rerolling into PHD from it will not reveal newly acquired pills.	All
Missing No./zh	Using Glowing Hourglass to go back to the previous floor will keep the rerolled items, which will allow to reroll them again.	All
Missing No./zh	Rerolling into PHD as Jacob and Esau will not reveal newly acquired pills, even if using the character that took Missing No.	All
Missing No./zh	Rerolling into PHD from it will not reveal newly acquired pills.	All
Missing No./zh	The Polaroid shield might not activate after the reroll	All
Modeling Clay	Walking between rooms back and forward with Modeling Clay may cause the game to crash at random.	All
Modeling Clay	Normally, Modeling Clay's appearance changes to reflect what item it's imitating. This is not the case if the trinket is absorbed, e.g. through Smelter. It will appear in the Found HUD where passive items appear, like other absorbed trinkets, but will never change its appearance.	All
Mom's Bracelet	Using Mom's Bracelet to throw a tile into Multidimensional Baby will turn the tile into two tears, and any pickups (such as Soul Hearts from Tinted Rocks) will not drop.	All
Mom's Bracelet	Infinite skulls can be farmed off of Hosts even though after initially removing the skull, the Host changes into a different variant.	All
Mom's Contacts	Enemies with multiple segments (Chub, Pin, etc.) can be petrified and have their segments destroyed individually, but continue to live with any remaining health. This can be problematic at times especially with Carrion Queen, as you could destroy the "tail" or center body segment when Carrion Queen is petrified, thus making you have to petrify her again, or use bombs to do damage.	All
Mom's Eye	Having a Mom's Eye, Technology and Technology 2 makes the back laser fire extremely fast.	All
Mom's Hand	Entering a room with a Mom's Hand/Mom's Dead Hand causes only very minimal screen shake. Spawning them with the debug console will cause a much more noticeable effect.	All
Mom's Heart	Sometimes, if the boss intro is skipped, the game will not teleport Isaac into the center of the bottom of the room, resulting in immediate contact damage with one of the Eyes or Mom's Heart, depending on the direction of the room's entrance.	All
Mom's Knife	Tiny Planet and Homing tears may cause a visual bug when there is a high range. This makes it look like the knife is going in circles when it's not rotating around the body.	All
Mom's Knife	With Tiny Planet, if Isaac releases the knife and exits the room before it returns to him, the knife will receive a significantly larger hitbox that scales with Isaac's Range. Releasing it and waiting until it returns will make it normal again.	All
Mom's Knife	Using Mom's Knife and Marked with Haemolacria will cause the latter to only fire towards the center of room. Using the fire buttons will barely move the Marked crosshair, while Mom's Knife will be unusable and locked to the right.	All
Mom's Knife	The Blindfolded condition also applies to the knives fired by Tammy's Head, and prevents it from working.	All
Mom's Lock	Mom's Lock will not contribute to the Yes Mother? transformation nor unlocking Mom's Contacts despite having the item tag.	All
Mom's Locket	Mom's Locket will not contribute to the Yes Mother? transformation nor unlocking Mom's Contacts despite having the item tag.	All
Mom's Pearl	Mom's Pearl will not contribute to the Yes Mother? transformation nor unlocking Mom's Contacts despite having the item tag.	All
Mom's Toenail	Because the position Mom's foot targets is random, it can land in the empty area of an L-shaped room.	All
Mom's Toenail	Mom's Toenail will not contribute to the Yes Mother? transformation nor unlocking Mom's Contacts despite having the item tag.	All
Monster Manual	Monster Manual will fail to spawn a familiar if it attempts to spawn Halo of Flies.	All
Monsters	Some Champion enemies that turn into another enemy when killed (Gurgle turning into Splasher for instance) become invisible.	PS4
Monstrance	When Pause is used with Monstrance it creates a second aura of light that stays in place where Isaac used "Pause" which lasts for the active item's duration. The second aura is a visual glitch and does not deal damage to enemies. Moreover, both auras are flashing for the duration.	All
Monstro's Lung	If The Forgotten obtains multiple copies of Monstro's Lung, he will swing 5 additional bone clubs in his melee attack per copy, up to a limit of 16.	All
Montezuma's Revenge	When playing as Tainted Forgotten, the charge attack will always come out of the left of the body regardless of the direction it or the Soul is facing.	PC
Montezuma's Revenge	When combined with Chocolate Milk, Cursed Eye, Monstro's Lung or Tech X, releasing a Montezuma's Revenge attack may prevent a charged shot from firing at the same time as expected. The charged shot is delayed by about ~0.5 seconds. Holding a full charge for a longer time makes the delay more likely to happen.	All
Mother	If Mother is killed using the "Quick Kill" debug flag, the final boss chest will not spawn, soft-locking the game.	All
Mother	Broken Modem may crash the game during the Mother fight at a random time, usually related to the wrist burst attack. The attack does not always cause a crash.	All
Mother	When entering the corpse for the first time: the item unlock screen for defeating Mother as the current character may appear, but the item nor the secret screen won't be unlocked.	All
Mother's Kiss	Mother's Kiss will not contribute to the Yes Mother? transformation nor unlocking Mom's Contacts despite having the item tag.	All
Mother's Kiss	While playing as characters who cannot have red HP, if Mother's Kiss is picked up while having 12 Soul/Black Hearts, Mother's Kiss will not trigger until damage is taken. However, if only half a heart of damage is taken, Mother's Kiss will immediately restore the health back to a full 12 but believe its effect failed due to not restoring a full heart's worth, allowing it to trigger again and again until a full heart of damage is taken, after which it will cease taking effect. If combined with The Wafer, this makes any of the aforementioned 6 characters virtually invincible as long as their health is not reduced in any way through Devil Deals, Health Down pills, etc.'"`UNIQ--ref-00000006-QINU`"'	All
Mother's Kiss	Dropping Mom's Box will not remove the second heart container until the trinket is dropped.	All
Mother's Kiss	Dying and respawning with Dead Cat will respawn you with only 1 heart container, meaning you will instantly die if you drop the trinket.	All
Mother's Shadow	If the game is saved and exited while in the sub-area, when it is continued, Isaac's visual appearance will match his items; however, items will still have no effect. It will revert to his plain appearance after either changing rooms or picking up a Throwable Bomb.	All
Mother's Shadow	Familiars with levels/stages will revert to their base form upon exiting the sub-area as the game does not internally store their levels. This includes, but is not limited to: Bumbo, Guppy's Hairball, etc.	All
Mr. Maw	Using the D10 on any monster with several pieces will reroll every piece into a monster. For the case of Mr. Maw, his cord dots are considered as pieces, and each will turning into a new monster.	All
Mr. Maw	If a Swinger's neck touches a red poop, the neck sometimes disappears while the Swinger keeps swinging.	All
Mr. ME!	If used while shooting with Marked, the crosshair will continue straight in the first direction Isaac shot at, and cannot be controlled until Marked is deactivated.	All
Mr. ME!	Mr. ME! is able to damage Mom's doors even when no body part is sticking out of them, Mom's Heart and It Lives while they're withdrawn, and Isaac and Hornfel while they're off-screen. He never loses them as a valid target, eventually killing the boss.	All
Mr. ME!	If attempting to explode an angel statue using Mr. ME! after ??? or The Lamb have been killed, the game will result in a crash.	All
Mucormycosis	During the Ultra Greed fight if a spore attaches to an Ultra Greed coin enemy, it may make the coins movement erratic and cause it to bounce around the room uncontrollably.	All
Mulligan	If a Mulligan or a Mulligoon is killed before the spawning period is finished (before they move), it will count as a self-detonation.	All
Mulligan	If a Nest is killed in the Burning Basement, it has a chance to spawn a Flaming Hopper.	All
Mulligan	Rarely if you kill a Drowned Hive before their spawn period is finished (before they move), it will shoot 4 projectiles in ordinal directions but the monster won't explode.	All
Multidimensional Baby	Can double Best Friend when it passes through.	Switch
Mystery Egg	When using Extension Cord with Mystery Egg, after the egg turns into a friendly enemy, the electricity shoots out into a random corner of the room.	All
Mystery Egg	When the egg turns into a friendly Heart ( Mask + Heart) will sometimes act as the heart companion for a mask already in the room resulting in an unbeatable room.	All
Obsessed Fan	When Isaac and Obsessed Fan are both moving and Extension Cord is held, the electricity will not always fully connect.	All
Onan's Streak	If Judas misses a tear and picks up the trophy while getting hit, he will be frozen in position. Going to the main menu and continuing the run solves this.	All
Panic Button	Spin to Win Has a chance to spawn additional wheels upon taking damage that last only for the current room.	All
Pause	If you activate and resume "Pause" while an enemy emits projectiles, the bullets won't proceed with regular but instead extremely decreased speed. However, they will still pass intended range, which bypasses the effect of shot speed being reduced as it normally would with any items that slow projectiles down.	All
Pause	When used with Dad's Ring/Monstrance/Saturnus it creates a second ring/aura/circle of light that stays in place where Isaac used "Pause" which lasts for the active item's duration. The second ring/aura/circle is a visual glitch and does not interact with enemies. Moreover, both rings/auras/circles are flashing for the duration. When used while Telekinesis is active Pause creates a second ring that stays in place where Isaac used "Pause" which lasts for Telekinesis's remaining duration. Moreover both rings are flashing and the second ring can not block enemy tears for the duration. Any tears that were still caught in Telekinesis’s radius before using Pause become incredibly slowed and indefinitely follow Isaac until he shoots. The items Salvation, Spear Of Destiny, and Trinity Shield all have a similar bug however these items are completely unable to interact with enemies (or block enemy tears for the shield) while Pause is activated.	All
Pause	When used with Star of Bethlehem the light aura will be stuck in the last position before Pause was used even if the familiar continues without it. This is only a visual glitch, Isaac still has to be near the star to receive its benefits. If Pause’s effect ends the light instantly disappears and respawns back around the star again. The light will still fade when the star leaves the room.	All
Pause	When used with Dark Arts, the player can unintentionally Soft-lock themselves if the Pause item is used during the effects of Dark Arts, this can be fixed by quitting then entering the game again. This is because Dark Arts does not finish its animation due to the pause item locking it in place. In addition to this, the player cannot escape this soft-lock via the fire button due to the player not being able to fire during the effects of Dark Arts. Moreover if this bug happens while Tainted Judas has Birthright, the dark aura around Tainted Judas will experience a visual bug from Pause that is similar to Monstrance.	All
Pay To Play	In Greed mode, it locks the Shop door and requires a coin to unlock it.	Switch
Peep	Peep's Eyes have the same collision radius as Peep itself, which results in the eyes being difficult to dodge since the hitbox doesn't match up with the eyes' visual size.	All
Pills	Any blue flies and blue spiders created by pill effects can be multiplied when Glowing Hourglass teleports Isaac in a way that does not move him to a different room from the one he is currently in (such as by teleporting to the previous room then using it again).	All
Pin	If you fire immediately upon entering the Boss Room, rarely, you can damage Pin before it emerges.	All
Pin	If Pin is under the effects of Broken Modem in mid-air, its jump will be stopped and it will fall.	All
Pitfall	Falling into a Pitfall while a Black Hole is active will result in Isaac becoming headless, immobile and invulnerable, softlocking the run until it is quit and resumed.	All
Pitfall	If Isaac walks over a Teleport Pitfall while Mega Mush is active a visual bug will occur where the pitfall is destroyed and can no longer harm Isaac however its sprites still remain in the room. When Isaac reenters the room or exits and continues the run, the teleport pitfall works normally again.	All
Placenta	Going into a Ventricle Razor portal at the same time the effect of Placenta is triggered will cause the effect to trigger in rapid succession, effectively healing Isaac to full health.	All
Plum Flute	If Baby Plum is spawned in a Crawl Space or The Beast fight, she will not properly bounce off walls.	All
Plum Flute	If Baby Plum is currently active when Tainted Lazarus swaps forms, Baby Plum will vanish. Once Tainted Lazarus swaps forms again, Baby plum will re-appear and continue her attacks. If she was doing her spit attack, her and her projectiles will end up stuck in place and she will not stop attacking until the player leaves the room.	All
Plum Flute	If Baby Plum is charmed by The Siren, her animation will freeze, she will stop firing bullets, and she will only be able to deal contact damage to Isaac.	All
Pluto	It is possible to throw a shrunken Tainted Forgotten exactly into the room corner, making it impossible to pick him up.	All
Poke Go	Glowing Hourglass: Each use of Glowing Hourglass that does not move Isaac to a different room than the one he is currently in (such as the starting room of a new floor).	All
Polished Bone	Each use of Glowing Hourglass that does not move Isaac to a different room than the one he is currently in (such as the starting room of a new floor) will duplicate friendly enemies.	All
Polty	Petrifying Kinetis while they are pulling a rock towards them causes the rock to keep flying and can cause it to fly out of the room.	All
Poops	If a poop is destroyed by an item pedestal spawning, collecting the item then leaving and re-entering the room will cause the poop to reappear, dropping its reward twice. This is especially remarkable for golden poops.	All
Poops	If a poop is pushed by an explosion to fill in a gap, a bridge will be created even if the poop survives the explosion. This way, it is possible to fill more than one gap with a durable poop such as golden poop.	All
Pooter	If a Pooter or a Super Pooter is stunned at the same time that it tries to shoot Isaac after the effect wears off, their shot will be fired without its corresponding animation.	All
Pooter	If a Pooter or a Super Pooter is stunned or feared at the same time that it tries to shoot Isaac, its sound effect will repeat continuously until the effect is gone.	All
Pride	If Pride is feared, only his head will be colored purple when he is facing the back wall of the room.	All
Pride	If Pride is slowed during his attack animation, he will not play the full animation.	All
R Key	If Sprinkler is used on the room the R Key is used in, the sprinkler will come with Isaac to the starting room.	All
R Key	If you use the R Key then spawn in a True Co-Op player and restart the game, the Co-Op players' active item and health will disappear.	All
R Key	If you use the R Key during a victory lap, then exit and re-enter the run, unlocks will be re-enabled.	All
Razor Blade	As Eve, there is a very unlikely chance that using this to activate Whore of Babylon will not activate it, despite being at the correct health to do so.	All
Reap Creep	If Tainted Forgotten's body is thrown next to the boss during Phase 3, it will continuously charge in place against the body, making for an easy kill.	All
Red Redemption	Being revived by Missing Poster / Broken Ankh or transformed into Esau Jr. removes the Red Key and does not allow you to open new rooms, soft-locking you.	All
Red Redemption	Exiting and continuing a run while more than one Dark Esau is present removes all but one. This can be repeated for every new Dark Esau keeping the total count at one while enabling the player to continue using the Red Key.	All
Repentance Co-Op	When one player is using Tainted Cain and takes a boss item pedestal, all items that aren't claimed will be taken immediately.	All
Repentance Co-Op	If Tainted Jacob is revived in his The Lost form and killed before the next floor starts, his ghost baby will be a floating Isaac head and turn into a floating Isaac torso when moving. This is purely cosmetic.	All
Repentance Co-Op	When an active item is on a boss pedestal and a player that already has an active item picks it up, any item underneath will despawn and only the replaced active item will be on the pedestal.	All
Repentance Co-Op	If Jacob & Esau is the last person to die in a co-op game, the game will not end and will instead softlock with neither of you able to leave the room. This is also true with Tainted Forgotten.	All
Repentance Co-Op	If multiple people are playing as Jacob & Esau, Esau's health will only be shown for the first player to join the game.	All
Repentance Co-Op	If you exit the game to the desktop and after returning to the game you click "continue" on a different controller/keyboard than the one you started the run with before, the second player's character will change into the character of the first player. Health bar of the second player will not be visible unless you exit to the menu and return to the game.	All
Repentance Co-Op	XboxOne When loading into a challenge, if the second player quickly presses left or right on the d-pad while spawning in the second player will be able to either choose random or Maggy, this random character will spawn with the items granted by the challenge along with their normal starting items, however their normal starting active will be removed. The hud for character selection will briefly appear if done correctly (This exploit is very inconsistent and can seemingly only be done while the first room of the challenge is fading in from the loading screen).	All
Repentance Co-Op	If Bethany dies by any source that removes heart containers (Guppy's Paw, Potato Peeler, etc.), she will respawn with one half soul heart / one and a half.	All
RERUN	Starting a RERUN with Schoolbag and two active items may copy the item in the "first" slot to both slots.	All
RERUN	Starting a victory lap with Card Reading will not work the first time you will walk on the portal. The second time it will work.	All
Revelation	When combined with Chocolate Milk, Cursed Eye, Monstro's Lung, or Tech X, releasing a Revelation attack may prevent a charged shot from firing at the same time as expected. The charged shot is delayed by about ~0.5 seconds. Holding a full charge for a longer time makes the delay more likely to happen.	All
Robo-Baby 2.0	Robo-Baby 2.0 cannot target Wall Creeps unless it is on top of one.	All
Rotgut	If Isaac is small enough (with Pluto for example), he can very easily clip through the ground during the Rotgut fight at phase 2 or 3 and enter I AM ERROR room, consequently skipping the fight to Corpse II. Dashing through the Maggot in phase 2 using items such as Mars or A Pony can also clip Isaac through the room, causing the same effect. This is also possible when Suplex! against its second or third phase.	All
Rotgut	If debug 10 ("quick kill") is active, Rotgut will get repeat its phase 1 death animation indefinetely, preventing Isaac from accessing phases 2 and 3, thus softlocking the game.	All
Rotgut	If Suplex! is used to kill Rotgut's first phase, the fight will fail to progress as instead of taking isaac to the next phase touching Rotgut will hurt him.	All
Rotten Baby	Rotten Baby will be able to spawn more than one friendly fly if the run is left and then resumed.	PC
Rune Bag	If one half of Tainted Lazarus holds this item, the Rune Bag will always drop the same rune for the whole run.	All
Sacrifice Room	Found HUD will incorrectly display Angel Room generation chance at 100% when receiving either of the "You feel blessed!" effects.	All
Sacrificial Altar	If used to sacrifice Succubus while Isaac is in its dark aura, the damage multiplier will remain active for the remainder of the floor.	All
Salvation	When Pause is used with Salvation it creates a second halo that stays in place where Isaac used "Pause" which lasts for the active item's duration. Moreover both halos are flashing and can not interact with enemies for the duration.	All
Satan	If exactly 600 HP of damage is dealt to Satan, it will completely skip the third phase and spawn the chest, due to how the boss is coded to go to the third phase only if over 600 damage is dealt. The easiest way to do this is to use only familiars to do damage, or to use 6 bombs (without modifications) against Satan's second phase.	All
Saturnus	Using Glowing Hourglass will trigger the effect of Saturnus again when returning to the room that was teleported out of, doubling the tears in that room.	All
Saturnus	When Pause is used with Saturnus, it creates a second circle that stays in place where Isaac used "Pause" which lasts for the active item's duration. The second circle is a visual glitch and can't hold any orbiting tears. Moreover, both circles are flashing for the duration.	All
Saturnus	In the first room of a floor, orbiting tears will appear elsewhere in the room and then be packed in two groups orbiting Isaac, instead of appearing on Isaac and then orbiting with an equivalent distance between each. They will turn back to normal when going to another room. This also happens in Mom's room after using her bed.	All
Schoolbag	Removing Schoolbag using D100, D4, or through being granted the effect from Metronome and using it again, does not cause the second active item to be removed or dropped into a pedestal; Isaac will still be able to hold his second active item until he picks up another active item, which will then remove the second slot and delete the active item contained.	All
Schoolbag	Re-rolling by a Dice Room removes the primary active item but the second one remains unchanged, allowing another active item to be picked up. Picking up another active item after this will result in the previous bug; the second slot is removed and the active item contained is deleted.	All
Schoolbag	As of V1.06.J168, the item inside the Schoolbag has a minor graphical glitch when picking up a third active item. For a single frame as the pickup animation ends, the item's "charged glow" status and number of bars will match the item that Isaac is picking up.	All
Schoolbag	When Isaac's Tears is in the first active item slot, the secondary item does not charge upon clearing rooms.	All
Schoolbag	If a player dies in True Co-op in the boss room, and the schoolbag drops an active item, because of the fact that boss item pedestals will spawn as many items as there are players, picking the active item back will spawn additional items up to 3. If the boss pool is gone through, it will start pulling from the treasure room. Once another Active item appears, any other items that could be gained through this method are (likely, needs more testing) unavailable.	All
Scolex	When Scolex is slowed, some of his body parts may detach or won't even show up - they will only be visible while entering the ground (especially the tail).	All
Scolex	If the final vulnerable segment of Scolex's tail is destroyed using the Chaos Card, the boss will glitch and become harder to kill. The tail will appear again if his head gets bombed or he hits Isaac.	All
Scolex	If you petrify Scolex (with Mom's Contacts or other similar items) when it is in mid-air, you can damage any segment of its body.	All
Scolex	If you fire immediately upon entering the Boss Room, rarely, you can damage Scolex before it emerges. The boss may also deal unavoidable damage sometimes if you immediately walk into the middle of the room after entering it.	All
Scolex	If Scolex is under the effects of Broken Modem in mid-air, his jump will be stopped and he will fall.	All
Scolex	If Scolex is frozen with Midas' Touch or Dad's Ring and attacked, he can split into two halves, one with his head and one with his tail.	All
Secret Room	After fighting Greed/Super Greed spawn inside a Secret Room, if there is an adjacent Challenge Room or Boss Challenge Room, the metal bars from the Greed/Super Greed fight will not disappear after the fight has ended, making it impossible to enter the Challenge/Boss Challenge room this way.	All
Secret Room	Teleporting to the Super Secret Room in Greed or Greedier Mode, when the room is generated behind a still-locked Treasure Room, can trap Isaac inside.	All
Secret Room	Curse of the Maze can move a room in a way that prevents creating a red room that connects to the Ultra Secret Room leading to a softlock.	All
Seed/zh	Entering the Blue Womb while using the "N0RE TVRN" seed is not recommended as the door leading to the Boss Room will not spawn, thereby trapping the player and ending the run.	All
Seed/zh	Returning to the menu from a run that uses a seed that alters the music speed will cause the main menu music to remain altered. This resets upon entering a new run, or exiting the game.	All
Seed/zh	The PAC1F1SM seed does not allow you to finish a The Beast run. Dogma never transforms in his second phase. If you manage to go to the Beast fight (with the debug console), the Chest spawns before Ultra Famine is killed.	All
Seeds	Entering the Blue Womb while using the "N0RE TVRN" seed is not recommended as the door leading to the Boss Room will not spawn, thereby trapping the player and ending the run.	All
Seeds	Returning to the menu from a run that uses a seed that alters audio speed will cause the main menu audio to remain altered. This resets upon entering a new run, or exiting the game.	All
Seeds	The PAC1F1SM seed does not allow you to finish a The Beast run. Dogma never transforms in his second phase. If you manage to go to the Beast fight (with the debug console), the Chest spawns before Ultra Famine is killed.	All
Shade	Shade will revert back to it's non-absorbed form after escaping Mother's Shadow.	All
Shoop da Whoop!	Using the item at the same time that you touch a large Golden Chest (dropped by final bosses such as The Lamb and ???) will freeze Isaac, and the ending won't appear. Leaving and re-entering the run will fix the bug.	All
Shopkeeper	Greeds spawned by blowing up Shopkeepers will play the incorrect boss music.	All
Sisters Vis	When there are four Sisters Vis (two pairs, which can be seen in Greed Mode) in the same room, there is a chance that three of them will act like normal, but the fourth one won't move or attack at all. However, when three are killed, the fourth one will return to normal.	All
Sisters Vis	When there are four Sisters Vis (two pairs, which can also appear in Chapter 4) in the same room, there is a chance that three of them will act normal, but the fourth will turn invisible after leaping into the air and not returning to normal visibility even after landing. It will keep its hitbox and can damage the player.	All
Sisters Vis	Sisters Vis can spawn in the bottom center of a Boss Room. If the entrance to the room is from the bottom, entering the room may cause Isaac to immediately take damage.	All
Skatole	Skatole's slowdown effect also affects Tumors and its variants, despite them not being flies.	All
Spear Of Destiny	If the Spear Of Destiny is removed from the player's items (for example, when using the D4), the spear will stay on in the level in the position where it was before the item was lost until Isaac moves to another room. This is purely a visual bug.	All
Spear Of Destiny	When Pause is used with Spear Of Destiny it creates a second spear that stays in place where Isaac used "Pause" which lasts for the active item's duration. Moreover, both spears are flashing and can not interact with enemies for the duration.	All
Spear Of Destiny	Swapping characters using Esau Jr. or as Tainted Lazarus will leave a stationary copy of the spear until Isaac leaves the room. The stationary spear is only visual, lacking collision.	All
Spear Of Destiny	The spear sometimes separates from the player.	All
SPEED!	During the Mom fight she does significantly fewer attacks, making the fight especially difficult as the only way to hurt mom is to trigger the hand attack.	All
SPEED!	If you successfully complete the challenge after the soft limit, you can still fail by taking ANY timer damage while the trophy-gathering animation is taking place. Taking timer damage during the trophy-gathering animation will cause your inputs to freeze and the trophy to disappear without actually finishing the challenge. You must either die or exit & re-enter the game if this happens.	All
Spin to Win	With Book of Virtues, leaving a room just before the item's charge runs out causes all wisps generated by Spin to Win to remain with Isaac, and will retain their very high fire rate. The wisps will orbit at their normal speed rather than the increased speed. Upon entering an uncompleted boss room, all wisps from this effect are extinguished immediately.	All
Spin to Win	On mobile, Spin to Win does not work. It spins for a singular frams, then deactivates.	All
Spirit Sword	When reaching 30.00 Tear Rate or higher, Spirit Sword will continuously use the spin attack, only stopped by holding down a fire key. This is likely due to the fact that starting at 30.00 Tear Rate, the internal number is "0", and begins to go negative beyond that.	All
Spirit Sword	In waterlogged rooms, the reflection of the sword swings in the opposite direction of the actual sword, when it should swing in the same direction.	All
Sprinkler	When switching to another active item via Schoolbag, sprinklers in the room will disappear.	All
Star of Bethlehem	If Isaac uses Pause, the light aura will be stuck in the last position before Pause was used even if the familiar continues without it. This is only a visual glitch, Isaac still has to be near the star to receive its benefits. If Pause’s effect ends the light instantly disappears and respawns back around the star again. The light will still fade when the star leaves the room.	All
Status Effects	If a non-boss enemy dies within 10 ticks (0.33 seconds) after being hit with a freezing tear or Cube Baby, it will be frozen regardless of what killed it.	All
Stone Grimace	Using the D10 in a room with Stone Grimaces will turn them invisible. They will not fire, but the space they occupied will prevent Isaac from moving through it like an invisible wall.	All
Store Credit	Buying a trinket (which is possible only in Greed Mode, as trinkets are not sold otherwise) while holding Store Credit will drop Store Credit without consuming it while still taking the trinket for free.	All
Store Credit	Buying free pickups with the Bag of Crafting doesn't remove the trinket.	All
Strawman	Box of Friends will not spawn a Demon Baby if Isaac has no familiars while Keeper is alive.	All
Strawman	If Keeper picks up Missing No., Strawman will not be removed from Isaac's inventory when Keeper dies and Keeper will not spawn spiders. Keeper will then respawn with no items upon picking up any familiar.	All
Strawman	Entering and exiting the Knife Piece 2 sequence in Mines/Ashpit II will remove any items from Strawman.	All
Succubus	If Succubus is spawned through Cambion Conception, its dark aura will not grant a damage multiplier to Isaac.	All
Succubus	If Sacrificial Altar is used to sacrifice Succubus while Isaac is in its dark aura, the damage multiplier will remain active until the remainder of the floor.	All
Sucker	Mama Flies are not affected by the Beelzebub transformation.	All
Suicide King (Challenge)	If the game crashes during the challenge and is reloaded, Lazarus will lose Ipecac and have his normal tears.	XboxOne
Suplex!	Using Suplex! in an room that contains normal floor tiles separated by pits or other obstacles Isaac cannot cross (without flying) may leave him stranded on the other side, effectively softlocking the game and ending the run. Isaac can usually get around this by exiting and resuming the run (returning him to the last door that was entered), but if a Crawl Space was entered first, resuming the run will place you there instead, meaning you're out of luck without using the console.	All
Suplex!	Using Suplex! in combination with Mega Mush makes you grab enemies and move them around until you leave the room. Doing this on any of the Ultra Harbingers or The Beast will make the enemy disappear and render you unable to move at all.	All
Suplex!	Using Suplex! on the White Fire will permanently extinguish it, preventing you from turning into the Lost any further and potentially locking you out of Knife Piece 1.	All
Suplex!	When Isaac leaps with an enemy that has a status effect it creates a visual bug where the effect is displayed over the enemy's head twice with one display following the enemy as Isaac leaps with them and the other display remaining static. This effect goes away once Isaac slams the enemy into the ground.	All
Suplex!	When using Suplex! with Tainted Jacob on Dark Esau, then using a pill while offscreen, it will cause Dark Esau to become fused to your body. He will not be able to hurt you, and he will stay stuck on you permanently until you are put into an animation (on hit, grabbing/using items,going to the next floor, etc;) which ends the bug, reverting him to his normal properties. It can also be used on anything that is or the game considers an enemy, (ex: Mom's Couch, Mom's Dresser, Shopkeepers, etc). It can also be used on bosses as well. Using this on either stage of Dogma will softlock the game.	All
Tainted Bethany	Certain items that spawn blue flies in large quantities can cause wisps to disappear.	All
Tainted Cain	In Co-Op mode, if Tainted Cain takes an item from the boss pedestal, he will take every other unclaimed item at once.	All
Tainted Cain	If you have Car Battery and you try to use an active item while you are using the Bag of Crafting, Car Battery will not work.	All
Tainted Eden	If Tainted Eden is firing Technology 2 when damage triggers a re-roll, sometimes the laser persists firing in the last-fired direction until leaving the room, even picking up new synergies as other items reroll.	All
Tainted Eden	If the active item is re-rolled into Alabaster Box it will be fully charged instead of discharged as usual.	All
Tainted Eden	If Tainted Eden first looks at an item on a floor (such as treasure room items, shop items, golden chest item drops, etc), but does not take them until after walking into a new room with an item in it (such as a Devil/Angel room), those items will be re-rolled into items of the pool most recently walked into.	All
Tainted Eden	If Tainted Eden rerolls into modded items that must be unlocked to be acquired, and they are not unlocked, the item will be rerolled into nothing, and you will lose an item. This can also cause crashes.	All
Tainted Eve	When Tainted Eve enters a boss room which moves her to a different starting position, such as Mom or Gurdy, the clots will not move with her, potentially leaving both Eve and the clots extremely vulnerable for a moment.	All
Tainted Forgotten	Evis can grab Tainted Soul. If Tainted Forgotten is not nearby, it can result in Tainted Soul having no way to kill the enemy.	All
Tainted Forgotten	Gaping Maws and Broken Gaping Maws can pull Tainted Forgotten inside them, rendering Tainted Soul unable to pick him up.	All
Tainted Forgotten	In rooms with reflective floors, while the Tainted Forgotten is being held, the reflection shows it below the Tainted Soul instead of over it, though its bone club is in the correct position.	All
Tainted Forgotten	If Tainted Soul is hit while Tainted Forgotten is holding Glass Cannon above his head, Tainted Forgotten will not be able to fire anymore.	All
Tainted Isaac	Sometimes items generated by TMTRAINER can bypass or reduce Tainted Isaac's item limit. Attempting to pick up a non-glitched item with a glitched item selected for replacement will add the normal item to Isaac's permanent inventory.	All
Tainted Isaac	Using Esau Jr. as Tainted Isaac can cause some items to bypass the item limit. One of the ways to do this is by having full inventory and a "quest" item (such as The Negative), and switch to and from Esau Jr repeatedly. After each switch, Tainted Isaac should replace at least one of his passive items. After a few switches, some item slots will appear to be empty or will depict the "quest" item(s). At that point, certain slots are bugged, and Tainted Isaac can take items, ignoring the limit if such a slot is selected. (more information is needed)	All
Tainted Judas	If Tainted Judas activates Glowing Hourglass right after the use of Dark Arts, he will be transparent like if he was using Dark Arts until he will use Dark Arts again. Other characters with Schoolbag also encounter this issue. This issue is purely visual.	All
Tainted Judas	Tainted Judas in his Dark Arts state can be affected by Pause, this results in Tainted Judas being stuck in his shadow form whilst not being able to fire any tears as long as Pause is still in effect, this can be fixed by quitting then entering the game again. Moreover if this bug happens while Tainted Judas has Birthright, the dark aura around Tainted Judas will experience a visual bug from Pause that is similar to Monstrance with Pause.	All
Tainted Lazarus	Exiting the run during the second or third wave of a Challenge Room will forcibly flip Tainted Lazarus when the run is continued.	All
Tainted Lazarus	If the player teleports out during an active Greed Mode wave, going back to the room will prevent the player from switching forms during waves until he reaches the wave that he was previously on. This is not the case if the waves were completed before the timer has ended.	All
Tainted Lazarus	Doing a RERUN when Birthright was obtained will spawn an additional alternate form of the character.	All
Tainted Lazarus	If Tainted Lazarus teleports (Mausoleum / Gehenna's teleporters or Stitches) at the same time as the room clears, he will NOT flip between forms.	All
Tainted Lazarus	If at least one character has Spear Of Destiny or Trinity Shield, swapping to the other character causes these items to leave a stationary copy of themselves until Tainted Lazarus leaves the room. The stationary spear is only a visual bug with no collision while the stationary shield still blocks tears.	All
Tainted Lazarus	Flipping while Baby Plum from the Plum Flute performs her spray attack and flipping again will cause Baby Plum to be stuck on Tainted Lazarus' position when he flipped.	All
Tainted Lazarus	Dying with Birthright and an item that revives as a different character (e. g. Judas' Shadow) will immediately kill that character upon revival, ending the run. Having more character-changing revival items will cause the character to die multiple times until there are none left. However, if Tainted Lazarus has a regular revive item that activates after the character-changing item (wihich is normally only possible with Guppy's Collar due to the order of activation), one of the forms will be turned into a different character while another will remain Lazarus. The unchanged form will flip in and out of existense as normal, while the other form will always be active. Quitting and resuming the run will require a controller to continue, and will then be played similarly to a Repentance Co-Op run.	All
Tainted Lazarus	Transforming into a different character while having Birthright will only transform the active form of Lazarus. The effects will be similar to the ones described in the previous bug (the unchanged form will flip in and out of existense as normal, while the other form will always be active).	All
Tainted Magdalene	Rotten hearts will not deplete when playing as Tainted Magdalene. Additionally, if you have more than 4 Rotten Hearts, Bone, Soul, and Black Hearts will not drain. If your pulsating heart containers are all filled with rotten hearts and and have more than one half a red heart in your permanent heart containers, your permanent red hearts will be drained.	All
Tainted Samson	Trying to Save&Exit and then Continue when having 0 HP during Berserk! will instantly kill you, even if the effect didn't wear off when you returned to the game.	All
Tammy's Head	With the Mom's Knife synergy, the Blindfolded condition prevents Tammy's Head from shooting knives and makes the item useless.	All
Taurus	Touching the chest after the ??? fight while the invulnerability is active will speed up the music during the credits. The music during Ending 14 and its "The End" screen will play as normal, however (This has not been confirmed for other endings or items that cause music to distort).	All
Tech X	The black ring generated from the synergy of Dr. Fetus and Tech X behaves as a Maw Of The Void ring and may cause black hearts to drop.	All
Tech X	Having Tech X with Soy Milk / Almond Milk and Kidney Stone causes Isaac unable to fire laser rings when Kidney Stone is active.	All
Technology	Having Technology, Technology 2 and Mom's Eye makes the back laser fire extremely fast.	All
Technology 2	Technology 2 prevents Lead Pencil and normal tears from firing if collected with specific items.	All
Technology 2	While playing as The Forgotten, holding fire as either The Forgotten or The Soul then switching to the other will create another Technology 2 laser in the direction being fired that persists until the room is left.	All
Technology 2	If Isaac is holding fire and has The Ludovico Technique while pulling out Urn of Souls, another Technology 2 laser is created in the direction being fired that persists until the urn is put away or the room is left.	All
Technology 2	Having Technology 2, Technology and Mom's Eye makes the back laser fire extremely fast.	All
Telekinesis	When Pause is used while Telekinesis is active it creates a second ring that stays in place where Isaac used "Pause" which lasts for Telekinesis's remaining duration. Moreover both rings are flashing and the second ring can not block enemy tears for the duration. Any tears that were still caught in Telekinesis’s radius before using Pause become incredibly slowed and indefinitely follow Isaac until he shoots.	All
Teleport 2.0	After all Mini-Bosses in Mini-Boss Rooms are encountered, on floors that would otherwise spawn Mini-Boss Rooms, they will not spawn, which results in Teleport 2.0 being unable to teleport Isaac to special rooms after the Mini-Boss Room in the teleport order, instead teleporting Isaac to the same room each time.	All
Teleporters	If Tainted Lazarus steps on a teleporter at the same time as the room is cleared, he will NOT flip to his other form.	All
The Beast	If the player has Knockout Drops, a sufficiently high amount of luck, and an item that fires multiple tears at once (such as Monstro's Lung), they will be capable of knocking the Ultra Harbingers far off the screen during The Beast's fight. This also occurs if the player has Strange Attractor and enough sources of tears being fired. Ocular Rift and Lodestone can provide similar effects.	All
The Beast	II - The High Priestess will always summon the foot on the right side of the screen, trying to target The Beast even during the fight with Ultra Harbringers. This will not deal damage to her, but can still hit enemies if they are close to the foot. Monstro's Tooth, however, works normally.	All
The Beast	If you get too close to The Beast during the inhaling attack, you won't be able to get out and will be stuck for the rest of the attack. This can be detrimental if you're playing Tainted Samson or The Forgotten, as The Beast will continuously deal contact damage.	All
The Bible	If The Bible is used on Mom with the Broken Remote trinket, it will not kill Mom and will instead teleport Isaac randomly to another room. However, this still unlocks The Halo as if Mom was killed with the Bible.	All
The Binding of Isaac: Afterbirth †	If an angel statue is broken inside the devil room the door will incorrectly be shown to be open, but can't be escaped from	All
The Binding of Isaac: Afterbirth †	When Scolex is slowed, some of his body parts may detach or won't even show up - they will only be visible while entering the ground (especially the tail).	All
The Bloat	The Bloat's eyes have the same collision radius as The Bloat himself, which results in the eyes being difficult to dodge since the hitbox doesn't match up with the eyes' visual size.	All
The Boomerang	The Boomerang can collide with The Ladder when deployed, causing it to immediately return to Isaac when thrown. It doesn't always happen.	All
The Forgotten	Making a deal with the devil that kills The Forgotten and switching into The Soul before ending the animation will make only The Soul playable, and vice versa. If The Forgotten is no longer playable, The Soul will be locked to the range of the chain. This will effectively softlock the run unless you also have Birthright.	All
The Forgotten	If The Forgotten obtains Brimstone right after the bone club is thrown (via effects like D4 or Dice Room or debug console), a barrage of knives is fired instead of a brimstone ball.	All
The Forgotten	If The Forgotten obtains multiple copies of Monstro's Lung, he will swing 5 additional bone clubs in his melee attack per copy, up to a limit of 16.	All
The Forgotten	Very rarely, The Forgotten's head will permanently vanish when picking up his first passive item. This bug remains unfixed even after restarting the game.	PS4
The Frail	If The Frail is under the effects of Broken Modem in mid-air, its jump will be stopped and it will fall.	All
The Haunt	When you kill the Lil' Haunts spawned by The Black Champion Haunt, there is a chance that the music will end as if you defeated the boss.	All
The Haunt	If phase 2 starts at the same time as Isaac inflicts a status effect on The Haunt, after the effect is gone, The Haunt will be permanently tinted with that status effect's color until it dies.	All
The Hollow	Sometimes this boss will get stuck in the wall when slowed.	All
The Hourglass	Upon using The Hourglass on The Hollow, there is a chance that when they hit the corners of the walls, they will stay there until the effect is gone. Afterwards, The Hollow will have the same moving patterns as Larry Jr.	All
The Ladder	In co-op, fellow players can stand on the ladder. If they do this and the player holding the item walks to another ledge, the ladder beneath player 2 will disappear, allowing him to walk on air.	All
The Lamb	If The Lamb is shooting projectiles and you damage it over half of its health, it will continue to fire until dead or it has finished its attack.	All
The Lamb	Killing the body in around 5 seconds will make the body stand inside of the chest, making you unable to reach it (and end the game). You can fix this by going in and out of the room.	All
The Lamb	With the special seed BASEMENT and coming with the last sacrifice room reward, opening The Lamb's chest makes the game crash.	All
The Lamb	If the body is hit with Little Horn effect after it is killed, it will be crushed by the Big Horn's hand and "die" again, causing Curse of Darkness effect to be applied a second time. The body is not destroyed by the hand, so this can be repeated indefinitely. Regular tears cannot hit the body after it is defeated, a beam attack such as Brimstone or Technology is needed to cause the bug.	All
The Ludovico Technique	Mom's Knife + Technology: Creates an uncontrollable laser ring centered on Isaac. The knife becomes stuck under Isaac and cannot be fired.	All
The Ludovico Technique	Inside any Crawl Space, including the Rotgut fight or The Beast and Ultra Harbingers fight, the tear generated by Ludovico Technique will disappear and reappear on top of Isaac occasionally.	All
The Ludovico Technique	At exactly 30.00 fire rate, the tear can only tick once on an enemy, potentially causing softlock due to lack of dps.	All
The Ludovico Technique	If Isaac is holding fire and has Technology 2 while pulling out Urn of Souls, another Technology 2 laser is created in the direction being fired that persists until the urn is put away or the room is left.	All
The Scourge	Tendrils are made out of many separate entities resulting in items that activate upon enemies dying, such as Hungry Soul or Infestation 2, to trigger multiple times at once.	All
The Siren	Charmed throwable familiars (such as Bob's Brain) can sometimes remain charmed after the cluster of familiars explodes.	All
The Swarm	Each use of Glowing Hourglass that does not move Isaac to a different room from the one he is currently in (such as by teleporting to the previous room then using it again) will duplicate orbital flies. Obtaining orbital flies by duplicating them can surpass the item's normal orbital limit.	All
The Visage	Using the console to spawn the mask by itself (id 903.1) will crash the game. All other parts of the Visage can be spawned safely.	All
The Visage	Some tear effects like little horn's combined with other explosive effects may glitch the chain's destruction, rendering Visage stuck in a permanent first phase stage without chains (or perhaps the game considers them still in place?). This softlock can only be avoided by some teleportation method or dying to it with extra lives, allowing for the player to start the fight over. To avoid the softlock, it is recommended to wait until Visage performs an attack and then destroying the chains, as this seems to be properly computed towards the progress of the fight.	All
The Void	A Stoney can spawn alone in a room, causing it to instantly die.	All
The Void	D12 can still generate trapdoors. Entering one will send Isaac into a different version of The Void.	All
Tinytoma	Each use of Glowing Hourglass that does not move Isaac to a different room from the one he is currently in (such as by teleporting to the previous room then using it again) will duplicate any smaller orbitals of Tinytoma currently orbiting Isaac.	All
TMTRAINER	In online, tmtrainer active items have no on use effects, only passive effects from actives.	All
Tooth and Nail	If Tooth and Nail is lost while in the statue form (e.g. through losing its Lemegeton wisp), Isaac will indefinitely remain in the statue form until he leaves the room.	All
Tooth and Nail	Using an active item with no cooldown repeatedly (Mom's Bracelet, Bag of Crafting, etc.) whilst in an invulnerable state will keep Isaac in that state.	All
Tractor Beam	Tractor Beam has unusual effects when combined with Continuum and Pop!.'"`UNIQ--ref-00000037-QINU`"' While shooting, tears will appear for brief moments at the back of Isaac's head, and if he hits an enemy with one of these, that enemy will be teleported to a corner of the screen for poorly understood reasons. Isaac himself can also get teleported to a corner, resulting in a potential softlock without flight or How to Jump.	All
Trinity Shield	When Pause is used with Trinity Shield it creates a second shield that stays in place where Isaac used "Pause" which lasts for the active item's duration. Moreover both shields are flashing and can not block enemy tears for the duration.	All
Trinity Shield	Swapping characters using Esau Jr. or as Tainted Lazarus will leave a stationary copy of the shield until Isaac leaves the room. The stationary shield still blocks tears.	All
Trite	If a Blister is scared, stunned, or shrunken, the Blister will still attack Isaac by chasing him or spawning Dark Balls.	All
Tuff Twins	The Tuff Twins can get stuck with the Bomb Grimace in the room.	All
Ultra Greed	If Ultra Greed is defeated at the bottom of the room, the ending chest will spawn incorrectly, causing it to be unreachable.	All
Ultra Greed	If Ultra Greed is hit by a Chaos Card after being turned into gold, his death animation will replay and cause a lot of gut splatter.	All
Ultra Greed	If the player dies and respawns outside of the room while Ultra Greed is rolling his eyes like a slot machine, the slot machine sound will play continuously until the game is paused.	All
Ultra Greed	Ultra Greed can 1-shot the player if they have Metal Plate, Cone Head, or other possible items.'"`UNIQ--ref-00000018-QINU`"'	All
Ultra Greed	If the player manages to constantly push back Ultra Greed while he charges so that he won't touch one of the walls, he will become stuck in his charge animation and won't do anything else until defeated. This can be easily done with Ocular Rift or Knockout Drops and a high amount of luck or tears.	All
Ultra Greed (Bosses)	Clearing the boss room before Ultra Greed's room will not charge Isaac's active item.	All
Uranus	If a non-boss enemy dies within 10 ticks (0.33 seconds) after being hit by a freezing tear, it will be frozen regardless of what killed it.	All
Urn of Souls	If Isaac is holding fire and has The Ludovico Technique + Technology 2 while pulling out Urn of Souls, another Technology 2 laser is created in the direction being fired that persists until the urn is put away or the room is left.	All
Vanishing Twin	Some familiars like Headless Baby will follow the other boss as if it was a familiar. After beating the boss, familiars that were after Vanishing Twin will get bugged and stay at the entrance of every room instead of following the player.	All
Vanishing Twin	Using IV - The Emperor while in a boss fight will immediately kill the twin boss and spawn the second item for free; the player will only have to fight one boss thereafter.	All
Vanishing Twin	In Double Trouble boss fights, only one of the bosses will get copied, but both of them will get their health lowered down to 75%.	All
Vanishing Twin	The interaction between this item and Great Gideon is unstable — attempting to kill a clone of Great Gideon with Chaos Card will sometimes fail and cause a softlock.	All
Vanishing Twin	When cloning Turdlet, Vanishing Twin will only clone 1 segment of the boss and will stick to it, making a 6-segments Turdlet.	All
Vengeful Spirit	Each use of Glowing Hourglass that does not move Isaac to a different room from the one he is currently in (such as by teleporting to the previous room then using it again) will duplicate the wisps. Any extra wisps created from duplication on a filled ring will appear at the entrance of each room Isaac enters and shoot in the direction Isaac is currently shooting.	All
Ventricle Razor	Entering one of the portals causes the Found Soul familiar to become invisible until Isaac drops and picks up the trinket again or enters a new floor.	All
Venus	When using D12 to reroll obstacles; any Movable TNT or Fire Places created within the charm aura will occasionally spawn as charmed for 2 seconds with only the pink tint to indicate the status effect. Corn poops created in the charm aura are unaffected however the Eternal Fly may also become temporarily charmed.	All
Vibrant Bulb	Replacing Isaac's active item with another active item that doesn't have a charge bar won't immediately activate the trinket's effects. The effect will depend on whether or not the previous item had a full charge or not. Furthermore, if the effect is active due to the previous item having a full charge, picking up a different active item that currently has no charge won't disable the effect, and vice-versa.	All
Victory Lap	Trying to pause the game when the player is asked if they want to do the victory lap disables the option and forfeits the victory lap.	PS4
Vis	If a Vis (or any of its variants) is stunned, scared, or shrunken, it will still attack the player while running away from Isaac.	All
Void	Sacrificial Altar is fully absorbed, unlike other single-use active items, allowing Isaac to sacrifice familiars and obtain Devil Room items with each activation of Void.	All
Void	If Isaac has overcharge from The Battery, using absorbed items that Isaac can "put away" (e.g. Shoop da Whoop!, Bob's Rotten Head, Eraser, and Notched Axe) will use all the overcharge, even when Isaac puts away the items. In the case of Notched Axe on its own, using Void will use all charges at once.	All
Void	Pedestal items do not vanish instantly upon Void usage, allowing for an item to be obtained despite using Void on it. While the animation when using the Void prevents picking up pedestal items, this can be circumvented by cancelling the animation (e.g. using bombs or timed damage mechanisms like Shard of Glass) or by having another player.	All
War	Grey champion War's 2nd phase doesn't have body sprites, so the game defaults to his normal appearance during that phase, unless he takes damage, in which case he turns red permanently (the same shade any enemy turns, briefly, when they take damage). This was fixed in Patch V1.7.8a.	All
Watch Battery	Watch Battery will not contribute to unlocking Jumper Cables despite having the item tag.	All
Wavy Cap	There is currently a bug on Playstation 4 and Playstation 5 where using the item causes the game to crash.	All
Wavy Cap	If the player continues a save after maximizing the use of the Wavy Cap, they will respawn with the fire rate increase and changed appearance, but none of the screen effects. The screen effects will return at the same intensity once a room is cleared.	All
We Need To Go Deeper!	If a trapdoor is spawned inside of a Black Market with this item and is entered, the player is trapped in the Crawl Space unless they go to the next floor.	All
We Need To Go Deeper!/zh	If a trapdoor is spawned inside of a Black Market with this item and is entered, the player is trapped in the Crawl Space unless they go to the next floor.	All
White Pony	If the Minecart is used while White Pony is active, the game will freeze and will need to be closed. The run will be able to continued normally.	All
Widow	The tint for the Pink Champion Widow does not show up as pink and looks like a normal Widow, but her attacks are the same spawns as pink	3DS
Wiggle Worm	The Tears up is not applied until Isaac's Tears are first increased by any other method.	All

The Binding of Isaac: Rebirth
Achievements Challenges Completion Marks Items Trinkets Characters Chapters Rooms Transformations Attributes Bosses Monsters Pickups Modes Curses Objects Seeds Effects Endings
Collection Item Pools Version History Modding Music