Transformations

Transformations alter Isaac's appearance and grant him special abilities.

A transformation occurs when obtaining at least three different items from a particular set of items.
These collectibles always share a particular theme that corresponds with the transformation.

Transformation Sets[]

ID	Name	Appearance	Description
0	Guppy		Grants flight and spawns a Blue Fly each time a tear hits an enemy. Grants flight and adds a 50% chance to spawn a Blue Fly when a tear hits an enemy.
1	Beelzebub		Grants flight. Converts small enemy flies into Blue Flies. Larger flies become friendly and follow Isaac between rooms.
2	Fun Guy		+1 Red Heart Container.
3	Seraphim		Grants flight and gives +3 Soul Hearts.
4	Bob		Isaac leaves a trail of green poisonous creep as he walks that deals 6 damage per second.
5	Spun		Gives +2 damage and +0.15 speed, and spawns a random pill upon transformation.
6	Yes Mother?		Isaac gains a stationary knife that trails directly behind him. It synergizes like Mom's Knife would.
7	Conjoined		Adds two tumors that fire diagonally from Isaac's head. -0.3 Damage, -0.3 Tears.
8	Leviathan		Grants flight and gives +2 Black Hearts.
9	Oh Crap		Whenever a pile of poop is destroyed, restores half of a red heart.
10	Bookworm		Roughly 25% of the time, Isaac shoots an extra tear, like 20/20.
11	Adult		+1 Red Heart container.
12	Spider Baby		Spawns a spider familiar that applies random status effects to enemies it comes in contact with.
13	Stompy	None	Taking damage has a chance to spawn rock waves. Isaac can break obstacles by walking over them.
n/a	Super Bum		Replaces Bum Friend, Dark Bum, and Key Bum with Super Bum. This bum collects any of the other beggars' pickups, and offers twice the rewards.

Requirements[]

Items only need to have been acquired once in order to count.
- Duplicate items (like those acquired from Diplopia) do not count toward transformations when picked up. Only the first instance of an item Isaac owns will count.
- Duplicate items are all counted.
- Activated collectibles (e.g. Guppy's Head) can be picked up once and then swapped away with another without any loss to transformation progress.
Rerolling items with a dice room, the D4, or the D100 will not remove progress towards the transformation.
- The transformation will be lost if the items required are rerolled or otherwise lost, eg. Sacrificial Altar. Items acquired by rerolling into them do not count towards any transformations.
Familiars gained from Cambion Conception or Immaculate Conception do not count towards transformation progress.
Trinkets do not count toward progress for any transformation, with the sole exception of Kid's Drawing that counts for Guppy transformation.
Pills only count toward Adult and Stompy, they do not count toward progress for any other transformation.
Characters that start with an item that counts towards a transformation do count as one of the three items needed for a transformation, such as Judas starting with The Book of Belial.
Familiars obtained through Soul of Lilith count towards the Conjoined transformation.
When playing as Jacob and Esau or Tainted Lazarus only the character that picks up an activated item first gets the progress for related transformations, however both characters in the set may undergo the same transformation if they both collect the remaining required set items left in the item pool.
Tainted Isaac will not lose a transformation nor progress towards it if he replaces an item that counts towards that transformation.

Notes[]

Transformations can be combined, keeping the effects of all transformations with no effects overriding others.
Transforming into Beelzebub for the first time will unlock the Lord of the Flies achievement and Angry Fly.
Since none of the Afterbirth transformations unlock an achievement or item, attaining them is not required for 100% completion of the game in terms of achievements. However, this is only true if you unlocked Mom's Contacts on Rebirth, as the Yes Mother? transformation will happen once you collect three Mom items on Afterbirth and Afterbirth †.
Many of the Afterbirth transformations override the charge animations of items such as Monstro's Lung and Brimstone, potentially making them more difficult to use.
- There is now an option to show a charge bar that floats above Isaac.

Gallery[]

Concept art drawn for transformations that would be implemented into the Afterbirth DLC.

Trivia[]

There are two transformations in the base game, nine more in the Afterbirth DLC, and four more in the Afterbirth † DLC.
In the original The Binding of Isaac flash game, the transformation into Guppy was the only one available, making it chronologically the first.
- The Eternal Edition of the original The Binding of Isaac game added another transformation that turned Isaac into an angel after gaining 7 heart containers from eternal hearts.
Rebirth introduced Beelzebub as the chronologically second transformation.
The original name for the Beelzebub transformation was Lord of the Flies.
The reason no new transformations have been added to Repentance is because Edmund and the dev team do not like them, as they view them as significant advantages gained only from being lucky enough to find specific items. This is why Guppy, the most powerful transformation, requires much more effort to get compared to a transformation like Spider Baby. If any new transformations were to be added, they would be purely visual.^[1]