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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 SetsEdit

Name Appearance Description Items

Grants flight and converts small enemy flies into Blue Flies.


Grants flight and spawns a Blue Fly each time a tear hits an enemy.


Isaac gains a green trail of poisonous creep.


When attacking, the tumor faces shoot tears diagonally outwards, similar to the effect of    The Wiz. Also gives -0.3 damage and slightly decreases tears.

  Fun Guy  

+1 Red Heart container.


Grants flight and gives +2 black hearts.

  Oh Crap  

Whenever a pile of poop is destroyed, health is replenished by half a heart.


Grants flight and gives +3 soul hearts.


Gives +2 damage and +0.15 speed, and spawns a random pill upon transformation.

  Super Bum  

Replaces   Bum Friend,   Dark Bum, and    Key Bum for Super Bum. This bum collects any of the other beggars' pickups, and offers twice the rewards.

  Yes Mother?  

Isaac gains a stationary knife that trails directly behind him. It synergizes like   Mom's Knife would.


Grants a heart container.


Roughly 50% of the time, Isaac shoots an extra tear, like   20/20.

  Spider Baby  

Spawns a spider familiar that applies random status effects to enemies it comes in contact with.

  Stompy None

Taking damage has a chance to spawn rock waves.


  • Items only need to have been acquired once in order to count. Keeping them is not required.
    • 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.
    • 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.
    •   Familiars gained from    Cambion Conception or    Immaculate Conception do not count towards transformation progress.
  • Trinkets do not count toward progress for any transformation.
  • Pills only count toward Adult and Stompy, they do not count toward progress for any other transformation.


  • 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.



  • 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 Binding of Isaac: Rebirth  
  Achievements   Attributes   Bosses   Cards and Runes   Challenges   Chapters
  Characters   Co-op   Items   Item pools   Monsters   Objects
  Pickups   Pills   Rooms   Seeds   Transformations   Trinkets