Blood Oath

Blood Oath is a passive item.

Effects

 * 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.

Synergies

 * 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.

Interactions

 * Gnawed Leaf: If Blood Oath stabs while Isaac is in statue form, he takes no damage but also receives no damage bonus.

Trivia

 * 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.

Seeds
R6HB VG08 (First floor curse room)