Monstro's Tooth is an unlockable activated item.
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 and deal 120 damage to whatever he hits. If there are no other enemies in the room, Monstro will aim for Isaac himself instead.
- 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. In addition, if it's used against an Eternal Boss, the summoned Monstro also changes to its eternal variant.
- Champion versions can cause additional effects (i.e. Red triggers Mom's foot to strike the 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.