Xxx form2Isaac Rebirth

Teratoma (テラトーマ Teratōma) is a boss added to the Wrath of the Lamb DLC. It resembles a posthumous version of Fistula.


It acts like Fistula, but spawns 3 medium sections instead of 4. Teratoma also spawns small Spiders when the smallest part of it is destroyed. It is a boss in The Womb I and Utero I.

Total HP: 60 (large) + 3x15 (medium) + 6x8 (small) = 153

In The Binding of Isaac: Rebirth, any room layout in the Catacombs and Necropolis that should contain Fistulas in WotL now contain Teratomas.

  • Be careful to not split off too many parts at once. This could impair your ability to dodge.
  • Anything that damages multiple enemies will help you speed up the battle (especially when a larger amount of sections are present on the screen)

Champion Variant



Eternal Teratoma is identical to normal Teratoma, but spawns 2 extra Spiders every time it splits.

When the final small Teratoma is destroyed, it spawns a Big Spider.


  • In biology, a teratoma is a tumor-like growth that contains normal tissue from each of three germ layers (like hair, teeth, or even bones). Like Fistula, these medical facts reference to their appearance (note the bones around Teratoma).



The Binding of Isaac / Rebirth
Regular bosses Original: BlastocystChubDuke of FliesThe FallenFistulaGeminiGurdyLarry Jr.LokiMonstroPeepScolex
(Wrath of the Lamb: Daddy Long LegsGurdy Jr.Mask of InfamyPinWidow)

Rebirth: Dark OneDingleGurglingsThe HauntMama GurdyMega FattyMega MawMr. FredPolycephalus
(Afterbirth: BrownieDangleLittle HornRag ManTurdlings)
(Afterbirth †: Big HornRag Mega)

Posthumous Bosses Original: Monstro II
(Wrath of the Lamb: The Blighted OvumThe BloatCarrion QueenThe HollowThe HuskLokiiTeratomaThe Wretched)

Rebirth: The AdversaryThe CageThe Gate
(Afterbirth: The ForsakenThe FrailThe Stain)

Alternative Bosses Original: C.H.A.D.GishSteven
(Wrath of the Lamb: Triachnid)

Rebirth: Sisters Vis (Afterbirth †)

Harbingers Original: WarFamineDeathPestilenceHeadless Horseman

(Wrath of the Lamb: Conquest)

Final Bosses Original: It LivesMomMom's HeartSatan
(Wrath of the Lamb: ???Isaac)

Rebirth: The LambMega Satan
(Afterbirth: HushUltra Greed)
(Afterbirth †: Delirium)

Seven Deadly Sins EnvyGluttonyGreedLustPrideSlothWrath
Seven Super Deadly Sins Super EnvySuper GluttonySuper GreedSuper LustSuper PrideSuper SlothSuper WrathUltra Pride
Angels / Demons Original: Krampus

Rebirth: GabrielUrielFallen Angels

The Legend of Bum-bo
Regular bosses BygoneDuskGibsGizzardaLoafPeeperPyreSangreShy GalThe Duke
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