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Revision as of 21:08, 2 December 2015 by (talk) (active item clarification)
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Transformations alter Isaac's appearance and grant him special abilities.

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

Transformation sets

Template:Transformation sets


  • Activated items (e.g. Guppy's Head) only need to be touched in order to count. Keeping them, or even activating them once, is not required.
  • Rerolling items with a Dice Room, the D4, or the D100 will not remove progress towards the transformation.
  • Transformations can be combined with each other, keeping the effects of any and all transformations with no effects overriding others.
  • Transforming into Beelzebub for the first time will unlock the Lord of the Flies achievement.
  • 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.


  • There are two transformations in the base game and nine 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.
  • Rebirth introduced Beelzebub as the chronologically second transformation. It is so far the only transformation that unlocks an achievement.