A black bat with large fangs.
Killing 13 monsters heals Isaac for a half-heart, indicated by a special sound effect and a small "health up" graphic.
If the kill counter reaches 13 while at full hearts, the counter resets and the heal is wasted.
- This item is useless to ???, since he cannot gain red hearts.
- Breaking down Globins into their goo-form will count as a kill. Therefore, letting them regenerate and breaking them down again can allow the player to restore health easily.
- XRay Vision - Allows the player to recover their hearts slowly yet indefinitely by repeatedly killing enemies in an uncleared room next to a Secret Room.
- IPECAC - The high damage of poison bomb tears makes healing a necessity, as well as being able to easily force doors open to exit an unfinished room and make monsters respawn for more kills.