Isaac's damage increases each time an enemy is hit. Damage is reset upon missing a shot.
Adds a chance to fire a booger which sticks to enemies and poisons them.
Spawns a familiar that drops random pills every 2 rooms cleared. Upon using a pill, all enemies in the room are poisoned.
Spawns a familiar that follows Isaac around and fires spectral tears.
Grants piercing and spectral tears. Increases tear size (without increasing damage) while greatly reducing range and shot speed.
Grants Isaac one full red heart container.
When hit, spawns up to 2 blue spiders.
Spawns a familiar that flies around the room in a manner similar to the Boom Fly and explodes on contact with an enemy. Respawns after ten seconds.
Spawns 2 keys. Generates additional pickups from chests.
Adds one filled heart container and increases Shot Speed.
Increases Damage by 1 and adds a chance to shoot fear tears.
Adds 3 black hearts and increases Damage by 1.
Each time Isaac kills an enemy, Isaac's damage increases for the current room.
+5 bombs. Isaac's bombs will now explode in a large cross-shaped pattern (roughly 5 bombs explosions wide). This also affects troll bombs.
Increases Speed and Shot Height and decreases Isaac's size, but lowers Range.
Drops a random trinket. Grants a second trinket slot.
Spawns a familiar that follows Isaac around and collects red hearts. For every one-and-a-half red hearts collected, Dark Bum will generate one soul heart, one hostile Spider or one friendly blue spider.
Crown of Light
Gives Isaac a crown that glows blue when active, and turns gray when inactive. While Isaac has no empty red heart containers, Isaac's tears are replaced with blue diamond tears that deal double damage. Regardless of health, the crown will deactivate for the current room when Isaac takes damage.
A familiar that follows behind Isaac. It drips a trail of creep, which slows enemies, and spawns 1-2 blue spiders after each room.