Conjoined

After picking up three baby familiar items from the following list ( 3 items with the baby item tag), Isaac grows two tumor faces from his cheeks, which fire simultaneously and diagonally similar to the effect of The Wiz, while continuing to shoot forwards. Decreases Isaac's damage by 0.3 and decreases Isaac's tears by 0.3.

Passive Collectibles

Name	ID	Quote	Description	Quality
Brother Bobby	5.100.8	Friends 'till the end	Spawns a familiar that follows Isaac around shooting tears that deal 3.5 damage. He shoots more frequently than most familiars.	1
Harlequin Baby	5.100.167	Double shot buddy	Spawns a familiar that follows Isaac around and fires two tears at once in a V-pattern.	1
Headless Baby	5.100.269	Bloody friend	Spawns a familiar that follows Isaac, leaving blood creep on the ground.	1
Little Steven	5.100.100	Psychic friend	Spawns a familiar who follows Isaac around and fires homing tears.	2
Mongo Baby	5.100.322	Mongo friend	Spawns a familiar that copies the tears of Isaac's other familiars.	2
Rotten Baby	5.100.268	Infested friend	Spawns a familiar that spawns a Blue Fly when Isaac shoots. It can only have one Fly at a time.	3
Sister Maggy	5.100.67	Friends 'till the end	Spawns a familiar that follows Isaac around shooting tears that deal 3.5 damage. Spawns a familiar that follows Isaac around shooting tears that deal 6 damage.	1
Abel	5.100.188	Mirrored buddy	Spawns a familiar that mirrors Isaac's movements and shoots in the opposite direction. Spawns a familiar that mirrors Isaac's movements and shoots towards him.	0
Acid Baby	5.100.491	Pills pills pills!	Spawns a familiar that drops a random pill every 3 rooms. Upon using a pill, all enemies in the room are poisoned.	2
Boiled Baby	5.100.607	Messy friend	Gives Isaac a familiar that fires chaotic bursts of tears in all directions.	1
Buddy in a Box	5.100.518	What could it be?!	Spawns a familiar with a random tear effect. The familiar is randomized at the start of each floor.	2
Cube Baby	5.100.652	Kick it!	Spawns an ice cube familiar that slides around when walked into. It slows and deals contact damage, freezing monsters it kills.	1
Cube Baby	5.100.652	Kick it!	Spawns an ice cube familiar that slides around when walked into. It slows and deals contact damage, freezing monsters it kills.	1
Demon Baby	5.100.113	Auto-turret friend	Spawns a familiar that follows Isaac and automatically fires at enemies in its reach.	2 1
Dry Baby	5.100.265	Immortal friend	Spawns a familiar that follows Isaac around and blocks enemy projectiles. Upon blocking a shot, it has a chance of triggering The Necronomicon effect.	3
Farting Baby	5.100.404	He farts!	Spawns a familiar that follows Isaac and blocks enemy shots. If a shot hits Farting Baby, it has a chance to fart, which charms, poisons, or knocks back nearby enemies.	1
Freezer Baby	5.100.608	Iced iced baby	Spawns a shooting familiar that has a chance to petrify enemies, and freezes monsters upon killing them.	2
Ghost Baby	5.100.163	Spectral buddy	Spawns a familiar that follows Isaac around and fires spectral tears.	1
Guardian Angel	5.100.112	Extra protection	Spawns an orbital familiar that blocks enemy shots, deals 7 damage per tick on contact, and increases the speed of all orbital familiars.	2 1
Incubus	5.100.360	Dark friend	Spawns a demonic familiar that shoots tears identical to Isaac's in terms of damage, tears, and tear effects.	4
King Baby	5.100.472	Hail to the king baby	Spawns a familiar that follows Isaac and makes other familiars follow it. While firing tears, other familiars stop moving.	1
Lil Abaddon	5.100.679	Abyssal friend	Spawns a familiar that charges a miniature Maw Of The Void attack while Isaac shoots.	2
Lil Brimstone	5.100.275	Evil friend	Grants a familiar that charges a thin Brimstone laser while Isaac is shooting.	2
Lil Loki	5.100.435	4-way buddy!	Spawns a Loki familiar that follows Isaac and fires 4 tears in a cross pattern.	1
Multidimensional Baby	5.100.431	ydduB Buddy	Spawns a familiar that will follow Isaac's movements on a 2.5-second delay. Tears that pass through the baby will be doubled and increase in speed.	2
Multidimensional Baby	5.100.431	ydduB Buddy	Spawns a familiar that will follow Isaac's movements on a 2.5-second delay. Tears that pass through the baby will be doubled and increase in speed.	2
Quints	5.100.661	They lurk inside	The first five enemies killed in a room will spawn stationary shooting familiars where they died.	2
Rainbow Baby	5.100.174	Random buddy	Spawns a familiar that follows Isaac around and fires tears with random effects.	1
Rainbow Baby	5.100.174	Random buddy	Spawns a familiar that follows Isaac around and fires tears with random effects.	1
Robo-Baby	5.100.95	Friends 'till the bbbbzzzt	Spawns a familiar that shoots Technology lasers.	1
Robo-Baby 2.0	5.100.267	We worked out all the kinks	Spawns a familiar that fires lasers at any enemy in its line of sight and moves based on the direction Isaac is firing tears.	1
Seraphim	5.100.390	Sworn friend	Spawns an angel familiar who follows Isaac and fires homing tears which deal 10 damage and have 75% shot speed.	3
Sworn Protector	5.100.363	Protective friend	Spawns an orbital familiar which does 105 damage per second and attracts and blocks enemy shots. Upon blocking 10 shots in a room, it drops an Eternal Heart.	3 2
Twisted Pair	5.100.698	Double trouble!	Spawns two familiars that float on either side of Isaac and fire tears that use his tears, range, shot speed, and tear effects, and scale with damage.	4
Lil Delirium	5.100.519	Delirious friend	Grants a familiar that transforms into another random familiar every 10 seconds.	1
Lil Delirium	5.100.519	Delirious friend	Grants a familiar that transforms into another random familiar every 10 seconds.	1

Notes

Isaac starts with this transformation in The Family Man challenge, but due to the challenge's blindfolded property, it's useless without Incubus.
Little Gish, Lil Monstro, Lil Delirium, and Lilith's Incubus do not contribute toward the transformation.
Familiars obtained from Cambion Conception, Immaculate Conception or Monster Manual do not contribute toward the transformation.
Familiars obtained from Soul of Lilith contribute toward the transformation.
Using Sacrificial Altar can remove Conjoined if it lowers the number of familiars below 3.