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 (or any of their variations) after clearing a room.

Interactions

 * : Familiar is bigger and increased chances for drops.
 * : Familiar will stay in place relative to Isaac.
 * : Familiar will occasionally be connected to Isaac via electricity.

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) 3CAR V7Z0 (First Golden Treasure Room)