- Grants half a red heart each time a key is used to unlock a door, golden chest, or key block.
- Turns half red heart pickups into full hearts. Half hearts already on the ground will also be upgraded upon re-entering the room.
- Having a Golden Key or Paper Clip will render the trinket unable to grant half hearts from keys.
- Having Mom's Locket while playing Keeper will restore a full health coin when a key is used.
- Donating keys to a Key Master won't heal Isaac.
- A very useful trinket for unlocking the It's the Key achievement, in which Isaac cannot pick up coins, bombs, and most importantly hearts.
- Hearts dropped from Tainted Magdalene's mechanic will be always full red hearts.
- With Tainted Bethany grants a blood charge upon using a key.
- Equality!: As long as Equality is active, all red hearts will be double.
- Humbling Bundle: Humbling Bundle cannot alter half red hearts, but Mom's Locket turns them into full red hearts, which it can double.
|The Binding of Isaac: Rebirth|
|Achievements||Attributes||Bosses||Cards and Runes||Challenges||Chapters|