A large bloody tooth, presumably from Monstro's mouth.


Isaac wears Monstro's Tooth as a necklace.

Upon activation, Monstro will jump down from above and land on a random enemy, if any. If there are none, Monstro will aim for Isaac himself.


  • To meet the Unlock condition, the following bosses must be killed at least once:
  • You can damage and kill the spawned Monstro if you're quick enough (i.e. freezing him or let him land into Satan's laser), but he won't drop anything.
  • The summoned Monstro can also be an alternatively coloured champion version instead of the normal coloured version.
  • Champion versions cause additional effects (ie, red triggers moms foot to strike area after short delay)
  • This item cannot be used on a fight against Monstro, but can be used on Monstro II.


  • If used on War when he drops troll bombs, War will become stuck and the player will have to restart the game.


Related Achievements

Monstrostooth "Monstro's Tooth" - Defeat all of the bosses in The Basement. (Duke of Flies, Monstro, Gemini, Larry Jr.)


  • In Rebirth, Monstro's Tooth has a sizeable crack in it.

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