Tainted Isaac

Tainted Isaac is a character added in The Binding of Isaac: Repentance. He is the alternate version of. Tainted Isaac is unlocked by reaching and using either the  or the  to access a special room in one of the walls while playing as Isaac.

Tainted Isaac can only hold 8 passive items at a time. Tainted Isaac's current 8 passive items are visible in the top-left corner of the screen, with one highlighted by a white square. Upon picking up a 9th passive item, the item currently selected, or rather the item currently in the white square, will be dropped on a pedestal in front of Tainted Isaac. The swap key can be pressed to cycle which item is selected.

In exchange for this, all rerollable item pedestals, Shop items, and Devil deals will cycle between two items for the player to choose from, essentially a stronger version of +. Whichever item is currently visible when the item is picked up will be the one selected. Once an item has been picked up it will no longer cycle between items.

,, , , , , , , the passive item created when Damocles is used (the one with item ID " "), and all activated items are exempt from this limit. Swallowed trinkets also do not count towards the 8 item limit.

Dropping items causes their passive buffs to be removed, however health or pickups will be kept (such as from or ).

Even if one of the item is a set drop, the other one is still randomly pulled from the current room's item pool.

Strategy and Items

 * Some passive items can be taken and left behind without their effect being reverted, such as HP upgrades like.
 * The stat upgrade of will not be reverted when left behind.
 * The stat shuffle of will not be reverted when left behind.
 * The temporary damage up of will not be reverted when left behind, but will still decrease over time as normal.
 * Stat changes from Pills are permanent. This can make them either extremely useful for stats allowing less stat up items to be held on to and make more room for other items or extremely detrimental as Tainted Isaac cannot counteract stat downs with items as easily due to only being able to hold eight items.
 * Transformations, including incomplete transformations, will not be reverted when items contributing to them are left behind.
 * Items that would add items directly to Tainted Isaac (such as, , etc) or pickups that would do the same (such as Soul of Lilith) do not take up an inventory slot.
 * In Co-op mode, the other character can pick up the items that Tainted Isaac drops but this item will no longer contribute to the transformation it is a part of.
 * Killing the Boss of a floor in Co-op mode will spawn a Boss item that cycles between two different options, but any subsequent options will not come with an extra choice.
 * is considered a passive item by the game and will take up one of Tainted Isaac's inventory slots.
 * If using the or  or  to reroll passive items, careful use can use these to accumulate heart containers in a way other characters can't.  Tainted Isaac doesn't lose heart containers when he drops a health item for a full inventory (unlike when health items are rerolled), so he can reroll to gain a health item and if he drops it instead of rerolling it the extra health persists, making it easier for him to accumulate more health containers.
 * Dropping or  will allow pills to become bad or good, respectively, but pills will remain identified after dropping the item(s).

Useful Items

 * and are extremely powerful with Tainted Isaac. Health ups and items that give one-time effects (such as ) can be traded out for a more useful item and then consumed for stat upgrades or red attack locusts.


 * gives Tainted Isaac four more item slots without taking up an item slot itself.
 * Birthright can be rerolled by items such as the, but it will only partially undo the effect of Birthright. If you had more than 8 items at the time of reroll, the extra items are retained above the usual limit.  These extra items do take full effect, and can be rerolled, but are not displayed and cannot be selected to drop next in the set of items.  Collecting Birthright again will show these extra items.
 * Butter!: When Tainted Isaac drops his active item, it is considered a "new pedestal," this means that the item will be given a second option, but it also fully charges the active item. It's considered a new Pedestal each time it drops, which means you can dig through an item pool for the exact item you want, assuming you're willing to drop your active item for it.
 * This synergy also allows for infinite (albeit slow) usage of any active item.


 * ,, , , and provide persistent stat upgrades.


 * and makes each copied pedestal rotate between the item that was on each pedestal at the time it was used and a random second item.


 * grants a random item at the start of your next run, even if you are to drop it and not finish your run with it.
 * When his inventory is full, he is able to swap it with another item from a pedestal. Every time GB Bug is picked up, the familiar will be re-summoned even if a room has not been cleared since the last re-roll. This allows Tainted Isaac to re-roll pickups indefinitely until they become chests, increasing the amount of pickups or giving items. However, the pickups may also re-roll into troll bombs, effectively removing a pickup to re-roll. This can be mitigated by having Safety Scissors.
 * , and do not take up inventory space, even after combining into the Knife familiar, allowing Tainted Isaac to gain extra damage without taking up any inventory slots.
 * respawns after being hit if swapped for another item and picked back up again, virtually guaranteeing rewards as long as Isaac's inventory is full.
 * ,, and can help Tainted Isaac build up a large amount of stat boosts via pills without having items tied to them.
 * can be used to generate and swallow trinkets for passive bonuses.
 * can be dropped when Tainted Isaac's inventory is full, which makes it easier to get clear benefit from than other characters. Tainted Isaac can carry from floor to floor until he rolls a useful combination of items, and then can choose to drop it so that it doesn't reroll his items on future floors.
 * can be used to generate trinkets for passive bonuses.
 * prevents any stat from decreasing, letting the effects of picked up items linger even after discarding them. However, raising stats beyond the values reached will be more difficult after leaving the source item, and swapping away Rock Bottom resets them to Tainted Isaac's current set.
 * If is dropped from the inventory when Tainted Isaac is holding two active items, one of those active items is also dropped, generating another item pedestal. This new pedestal cycles between the dropped active item and another item from the current room's pool. Tainted Isaac can take  and the active item again, and repeat the process indefinitely. This can be used to look for specific items in a given item pool, allowing for an easy way to get powerful items, such as  or, if done enough times.
 * If is dropped in this way, Tainted Isaac's bombs will no longer explode unless the item is picked up again and activated, making player's bombs useless without this item held.
 * can be used to absorb trinkets for passive bonuses.

Trivia

 * The achievement for unlocking Tainted Isaac is "The Broken". This is the name used in The Binding of Isaac: Four Souls.
 * Tainted Isaac's unlock for Ultra Greedier is the . Typically, this card symbolizes a lack of faith and despair. This is probably a reference to the fact that Isaac is shown to view himself as evil, and believing his only escape out is to end his own life.