D4

Effect

• Upon use, re-rolls each of Isaac's passive items into new ones.
  • (Removed in Afterbirth †) The new items will be drawn from the Treasure Room item pool.
    • (Added in Afterbirth † / Removed in Repentance) The game attempts to match the new item to the pool where the item it replaces was acquired but this is glitched, see the Bugs section.
      • If the item has no pool (gained as a starting item, fixed drops such as a Blood Bag from a Blood Donation Machine or The Virus from Lust, or gained via the debug console), the Treasure Room pool is used.
    • (Added in Repentance) New items are drawn from the pools the original items were from.
      • If health upgrade items are removed by a reroll the health they granted is subtracted.
        • (Tainted Isaac) Tainted Isaac can avoid this health subtraction by dropping health items for full inventory before rerolling.

Notes

• (Removed in Repentance) Items rerolled away from Isaac do not return to circulation and can't be encountered again.
  • (Added in Repentance) Items rerolled away are returned to circulation and can be encountered again later in the run.
• The D4 does not re-roll (Removed in Repentance) Dead Cat, (Removed in Repentance) Halo of Flies, Key Piece 1, Key Piece 2, Missing No., The Negative, The Polaroid, or (Added in Afterbirth † / Removed in Repentance) Tonsil.
  • (Added in Repentance) The D4 can reroll Dead Cat and Halo of Flies, but will not reroll Dad's Note, Damocles, Dogma, Knife Piece 1 and Knife Piece 2, in addition to the above.
• The D4 does not remove traits or abilities inherent to a character, i.e. (Azazel) Azazel's Brimstone-like attack, (Lilith) Lilith's Incubus or (The Forgotten) The Forgotten's Bone club.
• Items that grant pickups (like Pyro or A Dollar) do not remove their bonuses when rerolled.
• (Removed in Repentance) The D4 does not remove gained hearts from health up items.
• (Added in Repentance) The D4 does not give hearts that would be otherwise gained from item pickups.
• (Removed in Repentance) If Isaac has a transformation, its effects will not be lost upon re-rolling.
  • (Added in Repentance) Transformations are removed with the items being rerolled.
• The D4 can grant items that have not yet been unlocked.
• The items gained by the D4 count towards the collection page.
• (Added in Afterbirth / Removed in Repentance) If it is unlocked, (The Lost) The Lost starts with this item along with spectral tears and flight. Using it will reroll Holy Mantle.
  • (Added in Repentance) The Lost no longer starts with the D4. If used however, it will no longer reroll their Holy Mantle.
• (Removed in Repentance) Every Cube of Meat produced using (Added in Afterbirth †) Potato Peeler count as an item for rerolling to the D4. Because health usually is not removed in rerolling items this is useful to increase the number of items at the expense of the item pool.
• Multiple copies of the same item (as generated by (Added in Afterbirth) Diplopia, the Debug Console, or gathering them from multiple item pools (e.g. Steam Sale from both the (Shop) Shop and Greed) will each be rerolled into a different item, (Removed in Repentance) even though the duplicates are not present on the pause screen.
• There is a small chance that D4 will not reroll every item: the game makes a number of attempts to reroll each item, but if they all fail to produce a new item that is available and applicable, the original remains unchanged.
• (Added in Repentance) If used while playing as (Jacob and Esau) Jacob and Esau, it will only reroll the items on the character that used it.
• Smelted/Swallowed trinkets (via (Added in Afterbirth †) Marbles, (Added in Afterbirth †) Smelter or Gulp!) will not be rerolled.

Synergies

• (Added in Repentance) Book of Virtues: Removes all of Isaac's wisps and gives him one random wisp for every two items rerolled. Book of Virtues will not be rerolled in the process.

Bugs

| (Bug) Bug! | (Removed in Afterbirth) Previously held items are not removed from the pause menu, which makes it difficult to determine which items Isaac currently has. |

| (Bug) Bug! | When D4 is used with a co-op baby present, the baby's sprite will turn into a glitched sprite of Isaac. |

| (Bug) Bug! | If Tech.5 is fired while D4 is used, the laser will appear to continue firing for the rest of the room. |

| (Bug) Bug! | (Added in Afterbirth † / Removed in Repentance) If Isaac rerolls Schoolbag, he will keep both active items, but if he picks up a new active item it will swap with the one currently selected and the other will disappear. |

| (Bug) Bug! | (Added in Repentance) When Schoolbag is rerolled away while another active item is held along D4, the other active item will be dropped on a pedestal. Activating D4 after the other active item is dropped will then reroll D4 itself. |

| (Bug) Bug! | (Added in Afterbirth † / Removed in Repentance) The way the originating pools for items are tracked is bugged in two ways, making it possible for items to reroll into different pools.

1. An item picked up is assigned the pool of the most recently generated item; usually this has correct results but a difference can be seen, for instance, by killing a boss, entering a Devil Deal that has items and collecting the boss reward after seeing the Devil items. The boss item will be rerolled to a Devil pool item with D4.
2. Items that are rerolled are assigned the pool of the item with the highest item ID. This means one reroll with the D4 will probably go as expected, but further rerolls will be proliferated by items from the pool that had the highest ID before the first reroll. |