The Binding of Isaac: Antibirth Wiki

Mega Mush is an active item.


  • Gigantifies Isaac for a short duration. This effect persists across rooms.
  • While giant, Isaac gains the following effects:
    • Gains a significant buff to damage and range, but drastically decreases fire rate:
      • Damage is calculated in this formula: ( Effective(shown) damage + 1.5 ) * 4
      • Range is set to ~120.
      • Fire rate is halved.
    • Becomes invulnerable.
    • Can crush blocks and enemies.
    • Can bust through normal doors, Secret Rooms, and Super Secret Rooms.


  • This item allows Isaac to crush metal blocks and tall blocks, which cannot be destroyed by any other means.
  • While giant, Isaac cannot use any active items.
  • While active, Mega Mush will not be recharged by clearing rooms, while other active items gain charges normally.
  • Doors of Challenge Rooms, Mini-Boss Rooms, and Boss Rooms cannot be busted through. Locked doors still need keys to be opened.
  • Can randomly drop from exploded Mushroom blocks even before the unlock.

In-game Footage


  • This item is a reference to the Mega Mushroom from the Mario franchise.


2LDG 19LN (First floor secret room)