Binding of Isaac: Rebirth Wiki

Teratoma is a boss that can appear:

The large Teratoma has 60 HP, the medium forms have 15 HP, and the small forms have 8 HP, for a total of 153 HP.


  • Moves around the room slowly, bouncing off the walls.
  • When enough health is depleted, the one large Teratoma breaks into three medium Teratomas.
    • Medium forms behave identically, but move slightly faster.
  • Each of the three medium Teratomas breaks into two small Teratomas.
    • Small forms behave identically, but move very fast.
  • Each of the smallest Teratomas spawns two Spider Spiders on defeat unless they are over a pit or other obstacle.
  • All stages of Teratoma will do 1 full heart of contact damage.



  • Teratoma was added in the Wrath of the Lamb DLC for the original The Binding of Isaac.
  • It is the posthumous form of Fistula Fistula.
  • A teratoma is a tumor that contains tissues that are atypical for its placement in the body. This can include hair, teeth, bones, and so on.
  • Unlike the original Binding Of Isaac, Teratoma doesn't bounce off of Rocks.
  • Removed in Repentance Teratoma is one of the three bosses that can be spawned by It Lives It Lives, the other two being Chub Chub and Polycephalus Polycephalus.
    • Added in Repentance It Lives can now spawn Fistula as well.