The Void

This article is about the chapter. For the item, see Void. For the enemy, see Portal.

The Void is a chapter added in Afterbirth+. It is unlocked by defeating Hush. The Void is one of five final levels in The Binding of Isaac, alongside the Chest, the Dark Room, the Corpse, and Home.

Each room in this chapter takes the form of a different chapter, ranging from the Basement to the Chest and the Dark Room, including variant chapters like the Cellar and the Burning Basement. The Void is extremely large compared to other floors, and it is the only floor in the game (not counting XL floors) to contain multiple boss rooms. Most of them contain random bosses from other floors, including some of the final bosses, such as It Lives, Satan, Isaac, etc. One of them, however, contains the main boss of the floor, which is always Delirium.

Monsters encountered in The Void have a much higher chance of appearing as Champions.

The Portal monster is exclusive to this floor, and all rooms in which it would have been previously encountered on other chapters now only generate on this floor.

Access

After defeating Hush at least once, a new exit will appear in the upper right-hand corner of the 2x2 boss room in which Hush was fought. The new room contains nothing except for a Portal. It does not spawn enemies and serves as the entrance to The Void.

After unlocking The Void, the portal can then appear after every major boss starting with Mom, even if Hush was not defeated in that run.

The deeper the boss, the higher the spawning chance:

5% after Mom (Only if Isaac has 10+ tear damage or 20+ items)
10% after Mom's Heart / It Lives
15% after Isaac or Satan
20% after ??? or The Lamb
50% after Mega Satan (If the portal appears, the run will not end instantly like it normally does)
Defeating Hush will guarantee entrance to The Void.
- Defeating ???, The Lamb, Mega Satan, or Mother will also guarantee a portal.

Notes

The portal can appear multiple times during a single run.
- The chance for at least one portal to open after fighting It Lives, Isaac/Satan, and ???/ The Lamb is 38.8%.^[1]
- If Mega Satan is defeated, the chance for at least one portal increases to 69.4%.
After beating Mega Satan, there is a 50% chance a portal to The Void will appear with a chest instead of ending the run. Jumping into the chest will end the run normally.
If the portal spawns below Isaac's position after defeating a boss, he will immediately enter The Void.
Jumping into a trapdoor will reset The Void, an effect identical to Forget Me Now. This is useful if it has already been explored, but the player wants to clear more rooms to acquire health items before the final fight. The trapdoor must be found via a black market under rocks, as We Need To Go Deeper! and Rune of Ehwaz won't work.
Similarly, going to an I AM ERROR Room in The Void allows Isaac to reset the floor, so teleport items like Undefined can let Isaac repeat The Void multiple times.
The I AM ERROR room can be reached by leaving a Crawl Space through an unintended direction in the Chest and the Dark Room. The room will always contain a portal leading to The Void. However, any other method of getting to the I AM ERROR room will fail and generate an I am Error shopkeeper instead. Thus, the likelihood of this ever happening is practically zero without using items that can force the generation of the Crawl Space trapdoor, such as We Need To Go Deeper!
If the portal appears after Mom and the player chooses the Ascent path, the portal will still visually spawn on the way up. However, it is closed and can not be interacted with.
Once the Portal Entrance to the Void is spawned in a Boss Room, it will stay open even after leaving the room.

Bosses


Delirium

This floor contains multiple boss rooms, only one of which will contain Delirium. The other boss rooms contain a random boss from any floor including final bosses, except Mom, Mega Satan, Hush, Ultra Greed, Mother, Dogma, the Ultra Harbingers, The Beast, and all Repentance bosses that only appear on the alternate path.

Notes

Delirium's boss room is a 2x2 room, but appears as a 1x1 room on the minimap.
- Similarly, Mr. Fred's 1x2 room will appear as a 1x1 room if he spawns.
- Unlike normal boss rooms, Red Rooms can be created adjacent to these non-appearing rooms.
Items awarded from defeating bosses in The Void are generated as if Chaos was active, drawing from any item pool.
- If rerolled, the new items use the Boss item pool.
Since the Void has multiple boss rooms, using IV - The Emperor will teleport Isaac to one of them randomly.
Defeating a final boss in The Void that is not Delirium will not give a Completion Mark of that boss and will not unlock the respective item. It will however count towards other unlocks, like Triachnid for killing Isaac.

Locating Delirium

Main article: The Void/Locating Delirium

To locate boss rooms which will most likely contain Delirium, Isaac must look at the boss rooms on the map:
- Try to find a boss room that would not be connected to other rooms if it was a 2x2 room. If it would connect, the room won't contain Delirium.
- Remember that the boundaries of the map are at a maximum of 13x13 squares. If a 2x2 boss room would extend past those boundaries, that room cannot contain Delirium.
By knowing which boss rooms cannot contain Delirium, Isaac can safely enter certain boss rooms to gather items before fighting Delirium, or not enter these boss rooms knowing that Delirium is not there.
Entering boss rooms with a teleport card is also smart in case you encounter Delirium.

Gallery

The red "floor" of the Void.
The Void's icon on the Progress Bar.

Trivia

It is implied that the different forms (floors from chapters 1 to 6) of this floor are just Isaac's hallucinations, as the Void's icon on the progress bar (after advancing to the next floor) is a red vortex, and the "floor" graphic (below the player character and bosses in "VS" screens) is a red vortex as well.
On Isaac's last will, The Void is referred to as "some dying memory".
Occasionally, there will be a static distortion and the background and objects of the room may change to those of other chapters.
Mom's Heart can still spawn as a boss, even after being replaced by It Lives in Chapter 4.
The Void is the only floor that can be cleared indefinitely with Undefined (or Teleport 2.0 plus The Battery or a guaranteed Lil' Battery drop).
The champion enemies spawned in The Void will never drop any of their assigned drops.
The Void can be entered in Greed Mode by entering "stage 8" in the Debug Console. The rooms have random backdrops and the music is the same as The Void in regular mode, but the boss is Ultra Greed and will drop the Final Boss Chest. Entering the chest will play Ending 20 instead of Ending 18 or 19.
- The "stage 8" floor has no name, no music and plays no ending when entering the Chest.
The starting room and the boss rooms of The Void do not have the visual effects of the environment they're based on (i.e. a boss room with a Womb backdrop will not have the red static of the Womb).
- Also, Caves-based rooms do not have the visual effects of Caves.
Even if a boss isn't unlocked (i.e. Sisters Vis before beating ??? 6 times), it can still appear in one of the boss rooms.
An unused floor found in Repentance sharing the name "The Void" can be found in the game's files and contains a variety of unique unimplemented rooms, some of which feature Repentance bosses.
- This may have been related to the Delirium revamp which Kilburn noted in a tweet.^[2]
As of Repentance, The Void is the only chapter in which the boss VS screen is completely black, as opposed to having a slightly coloured shade to represent the current chapter/environment Isaac is in.

Music

The music that plays in The Void is titled Terminus.^[3]
- The track appears to be a remix of boss themes, Genesis 22:10 (title screen), and the Basement and the Burning Basement themes.