Leech

This article is about the item. For the monster, see Leech (Enemy).

Leech is a passive item.

Effect[]

Spawns a crawling Leech familiar that follows Isaac. If an enemy comes near, the Leech will attack and chase it, doing 1.5 damage per tick or about 3.2 damage per second. If an enemy is killed by the Leech, Isaac will be healed by a Half Red Heart.

The Leech's healing effect does not affect characters that do not have Heart containers.
- Keeper/ Tainted Keeper will be healed by The Leech.
Enemies that turn into flesh piles and regenerate when killed such as Globins and some dark red champions regenerate quicker than the Leech can kill them. Isaac will gain half a heart each time the enemies collapse, granting an easy way to regenerate all Red Hearts. This can also open up many powerful synergies with any item that provides a benefit or resource when Isaac takes damage.
Like Ghost Baby can drop from skulls, Leech can rarely drop from the buckets in Downpour.

Arcade rooms: The player can let the Leech eat Flies from the Shell Game and use the resulting health to gamble on the Blood Bank.
BFFS!: Leech grows bigger and does double damage. Still only heals for a Half Red Heart.
E Coli: Enemies can be turned into poop at the cost of a Half Red Heart, then consumed by the leech to regain health. Utilization of temporary immunity when hit can allow multiple enemies to be turned into poop, resulting in a net gain of health.
Flush!: The leech still can attack the enemies turned into poop and gain health.
Gnawed Leaf: The player can stand still and allow the Leech to clear a room, granting simple clears and easy health.

Tainted Bethany: Due to the fact that Tainted Bethany’s Lemegeton gains charges with red hearts, leech can charge it up by killing enemies.

Bug!	Tends to get confused when attacking Maggot like enemies and just moves around in the attacking animation without attacking anything until the Maggot is killed by The Player.