
Isaac's Fork - When clearing a room, provides a 10% chance of healing half a heart.Isaac's Head - Provides a familiar which is similar to Brother Bobby, but with piercing tears.Flat Penny - 50% chance of spawning a key when picking up a coin.Fish Head - Attack flies spawn every time Isaac gets hit.Eve's Bird Foot - Chance to spawn a Dead Bird when attacking an enemy.Cursed Skull - If Isaac's health is brought down to 1/2 of a heart, he is then teleported to a random room.
Counterfeit Penny - 50% chance of increasing coin value on pickup. Child's Heart -Increases the chance of receiving hearts from drops. Cain's Eye - 25% chance of Compass effect at the start of a floor. Burnt Penny - 50% chance of (collectable) bomb spawning when picking up a coin. Bloody Penny - 50% chance of dropping 1/2 heart upon picking up a coin. Ace of Spades - Improves chances of finding cards. ?'s Soul* - Provides a familiar that shoots homing spectral tears. Unlike with Mama Mega!, Mom's Heart / It Lives must be beaten for the passageway to ? to open. Leaving and re-entering the room after switching to the correct character will open the door normally. If playing with modal characters such as Tainted Lazarus, the character with the Strange Key must enter the room while holding it to cause the passage to open. Using Pandora's Box with the key in this state will remove the key from Isaac's Inventory. Both effects work even if the key has been turned into a passive item from items such as Smelter or Marbles. The Treasure Room item pool has a much higher chance to be chosen while the others have an equal chance. The items are chosen from the following item pools: Treasure Room, Shop, Boss, Devil, Angel, Secret Room, Library, Golden Chest, Curse Room and Planetarium. Both Pandora's Box and the trinket are consumed. The normal effect of Pandora's Box for that level is ignored, and instead 6 generally higher quality items from a set of item pools are spawned.
If Pandora's Box is used while holding Strange Key, the following effects will occur instead of Pandora's Box regular effects:. Unlocks the passageway to ?, regardless of run duration.