Binding of Isaac: Rebirth Wiki

Added in Afterbirth †

D1 is an unlockable activated item added in The Binding of Isaac: Afterbirth †.


  • Duplicates 1 random pickup in the current room, including Cards, Runes, Chests, and trinkets.
  • Added in Repentance Duplicated pickups may not be identical to the original; for example, a duplicated card may be a different one than the original.


  • Rune of Jera Rune of Jera can not be duplicated.
  • Mimic Chests will not be duplicated.
  • Opened chests will be duplicated into an unopened copy.
  • It is possible to duplicate Shop Shop pickups that have not been purchased yet.
  • Removed in Repentance By dropping a card, rune, or pill in a room with no other pickups, then using D1, this item can function similarly to Blank Card Blank Card and Placebo Placebo.
  • Removed in Repentance A normal Chest may be duplicated into a Red Chest or a Mimic Chest.
  • Removed in Repentance A duplicated trinket is mostly useless, as you cannot pick up two of the same trinket even with Mom's Purse Mom's Purse, Belly Button Belly Button, or Smelter Smelter.
  • Removed in Repentance With Car Battery Car Battery, it is possible to infinitely generate Lil' Batteries from a single Lil' Battery.
    • Added in Repentance While it's still possible to generate infinite batteries with this synergy, it is very slow to do so since mostly Micro Batteries will spawn. The occasional Lil' Battery or other battery spawn is needed to build up the battery pile.
  • Removed in Repentance In combination with a 48 Hour Energy pill and Paper Clip Paper Clip, the initial Locked Chests on Chest Chest can be infinitely duplicated and opened.
  • Removed in Repentance In Greed Mode, if a Lil' Battery appears in the Shop Shop and a 2 of Diamonds 2 of Diamonds is acquired, infinite money can be gained by duplicating the Two of Diamonds.
  • Added in Repentance A duplicated card has a chance to turn into Added in RepentanceCracked Key Cracked Key; however, a duplicated Cracked Key will always turn into another Cracked Key.


  • Added in RepentanceBook of Virtues Book of Virtues: Spawns two white six-sided die wisps, on the middle ring, at the same time. An extra wisp spawns if no pickups are duplicated.
  • Added in Repentance Tainted Lost Tainted Lost: Duplicated cards have an increased chance to be Holy Cards.

In-game Footage[]


  • Removed in Repentance D1 is the only die item that doesn't re-roll anything.
    • As such, its description, in certain cases, can be ironic, as the outcome is entirely predictable if there's only one pickup. This makes sense because the die only has one pip on each of its 6 sides.
      • Added in Repentance The D1 now creates randomized pickups, meaning that the description is more accurate to the items effect.
    • As an exception, Added in RepentanceSpindown Dice Spindown Dice, although it technically does re-roll items, has a controlled and consistent result.
  • D1 is the only standard die item that doesn't have the respective number of sides as outcomes, but rather, just a D6 with all sides having singular pips. Rather, an actual D1 would be more accurately pictured as a Mobius strip or a sphere.


PC Normal and hard modes only 34HF 9E4F (Treasure Room adjacent to spawn)