Penance

Penance is an unlockable passive collectible added in Revelations Chapter One, and was reworked in Chapter Two.

Achievements

 * achievement penance.png Unlocked Penance - Defeat Mom as Sarah.

Effects

 * All spawned Soul Hearts pickups are replaced with Black Hearts, as well as Soul Hearts gained through other means (such as Book of Revelations).
 * Soul Hearts already collected or spawned before obtaining Penance are unaffected.
 * When returning to rooms with uncollected Black Hearts, any Black Hearts in the room will immediately transform into spirits and fly off-screen.
 * Upon taking Black Heart damage while in combat, all of the player's Black Hearts will be removed and reform as spirits.
 * Each Black Heart will spawn one spirit. These spirits will move to one of the cardinal sides of the player, charge for a moment and dash across the room, dealing contact damage to the player and enemies.
 * After combat is finished, the spirits will disappear and black hearts will be restored with no damage.
 * If a spirit hits the player twice in the same room, it die and not go back to the player at the end of the room.
 * Taking Black Heart damage outside of combat damages the player normally. This includes challenge rooms, as they start cleared.
 * If Black Hearts are the only type of heart the player has, taking damage in combat immediately kills the player no matter how many Black Hearts they have.
 * All Angel Rooms are replaced with a unique layout featuring an Angel statue with a broken wing that offers no items normally.
 * Upon entering, the Angel will fully refill the player's Red Hearts and remove all the player's Black Hearts.
 * Upon removing a certain number of Black Hearts, the Angel will reward the player with an item from the angel room pool, alongside additional rewards depending on how many times the player has been rewarded.
 * The number of Black Hearts required begins at 1, then increases by 1 for each time the player was previously rewarded in that run (to a maximum of 5 required).
 * The 2nd reward will always drop a Gold Heart alongside the item.
 * The 3rd reward will always drop a Eternal Heart alongside the item.
 * The 4th reward will always spawn an Eternal Chest alongside the item. Additionally, when playing as Sarah, flight is granted.
 * The 5th reward and onward will always spawn both an Eternal Chest and a Eternal Heart alongside the item.
 * Black hearts not turned into rewards will return to the player when leaving the room.
 * Blowing up the Angel statue will start an Angel fight as usual, but will unleash spirits of all unused black hearts, with 1-2 extra spirits.
 * All the spirit left after defeating the Angel will be retrieved, allowing the player to get extra black hearts for the next floor if the extra spirits survive.
 * When not playing as Sarah, Penance acts like Duality; whenever a Devil or Angel room spawns after defeating a boss, the other will also spawn. The room not chosen will disappear.