The Binding of Isaac: Antibirth Wiki
Blood Oath
Blood Oath Icon.png
Character Appearance
Blood Oath App.png
Item Type
Passive Collectible
Item ID
Pickup Quote
Bleed me dry
Item Pool
Curse Room
Devil Room

Blood Oath is a passive item.


  • Stabs Isaac at the beginning of each floor, draining all but half a heart of his red heart containers.
    • Increases damage and speed each time Isaac is stabbed. The stat increases the scale with the amount of health lost.
    • Isaac can avoid damage from Blood Oath with invincibility, but he won't gain the damage and speed increase if he does.
    • If Isaac is already at half a red heart, no blood is taken and no stat increase is granted.


  • It is possible to prevent red hearts from draining while still gaining the stat increases, as long as Isaac's speed is high enough to immediately leave the starting room.
  • This item does not affect The Lost or ???; they don't take damage and get no stat increases.
  • Being stabbed does not remove Eternal Hearts.
  • If Isaac has Rotten Hearts, each Rotten Heart leads to the loss of half a Soul Heart.
    • If Isaac does not have enough Soul Hearts, he will die.
  • Being stabbed does not affect the chance for Devil/Angel rooms to appear.
  • If more than 1 Blood Oath's are picked up, Isaac's health will be brought to 0


  • Bloody Lust: Damage taken by Blood Oath at the beginning of the floor triggers the Bloody Lust damage bonus for each half-heart lost. By losing more than 3 Red Hearts, it is possible to gain the max damage bonus of Bloody Lust at the beginning of the floor.
  • BFFS!: Increases the amount of damage Blood Oath gives you.
  • The Habit: Grants 1 charge per half-heart taken by Blood Oath.
  • Menorah: Lights one candle per half-heart taken by Blood Oath.


  • Gnawed Leaf: If Blood Oath stabs while Isaac is in statue form, he takes no damage but also receives no damage bonus.
  • Book of Shadows : If the book is used before the knife stabs Isaac, he will not lose any health nor gain any stat upgrades that come with the loss of hearts. This interaction makes the book incredibly useful in the Bloody Mary challenge.

In-game Footage[]


Bug Bug! If the player has at least one Rotten Heart, damage from Blood Oath takes away every red heart, usually resulting in immediate death unless the player has soul hearts.


  • This item originated from the Binding of Isaac: Community Remix mod. However, it just gave a damage bonus that degraded linearly with red health.
  • The appearance of the familiar changes depending on the amount of health it has taken on the current floor: it stays clean if no health was taken and becomes bloodier the more health was taken.


R6HB VG08 (First floor curse room)