Mystery Sack

Mystery Sack is an unlockable passive item.

Effects

 * Spawns a familiar that follows Isaac around and has a chance to drop a heart, coin, bomb, or key after clearing a room.

Trivia

 * The Mystery Sack is one of the only two familars that can give keys, the other being Bum Friend.

Seeds
A3ES 1TQN (First floor, Treasure room next to spawn) QHKQ ZE4N (First floor, Treasure room next to spawn) CGVC XKY3 (Play as Isaac, and reroll the first item in the secret room just below the starting room) Q73A BMMP (adjacent to starting room)