Tainted RIsaac is an unlockable character in The Bimbing of AIsaac, a mod for The Binding of Isaac.

Locked Heart (consumable slot)

• 3 Key Slots

Key Ring (key slot 1)
Key (key slot 2)
Key (key slot 3)

Health is replaced with keys. Each Key Slot can hold only 1 key.

The Drop button allows to scroll through key slots.

When Tainted RIsaac picks up a key, it will be placed in the selected key slot if it is empty, otherwise it will be placed in the first empty slot from left to right.

Trying to open a door, open a chest or doing any other action that consumes key will use up the selected key.

Locked Heart can be used to absorb the selected key, increasing Locked Heart's XP (XP bar is represented by the chargebar).

When Locked Heart is fully charged, it levels up and gives +1 Key Slot.

The formula for the amount of XP required to level up is 5 + level*3.5. (Locked Heart starts at level 0)

Devil deals cost Key Slots instead of hearts.
(If the removed slot had a key in it, the key will be automatically absorbed by Locked Heart)

Keys take damage from right to left, just like regular health. (Hearts in the heart bar correspond to the keys in Key Slots)

If no keys are guaranteed to block the damage, the Core heart (the purple one) becomes exposed. (the keys that have only a chance to block damage are ignored)

While Core heart is exposed, deal damageStat * 1.5 / (1.5 + KeySlots) to every enemy every second.

There are many new keys that are only available as Tainted RIsaac.

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Keys and their corresponding health
• Key - Can take up to 2 damage, then breaks. (identical to Heart (soul))
Regular keys spawn 50% less as Tainted RIsaac.
XP:1

• Key Ring - Can take up to 3 damage, then breaks.
After taking damage, if there is still health left, will turn into Key.
When used as a key, turns into Key instead of disappearing completely.
XP:3

• Golden Key - Can take up to 4 damage, then breaks.
When breaks, explodes like a Gold Heart.
XP:10

• Charged Key - Can take up to 2 damage, then breaks.
Clearing rooms gives +1 charge to active items.
XP:7.5

• Spikey Key - Can take up to 2 damage, then breaks.
When takes damage, deals 15 damage to all enemies in the room. (Triggers twice if both halves were destroyed in one hit)

Has a chance to replace Black Heart.
Has a chance to replace Heart (soul) in Curse rooms.
XP:2.5

• Boss Key - Can take up to 2 damage, then breaks.
Grants +0.25 flat damage for each half of this heart.
Replaces the boss room item.
XP:2.5

• Yek Ssob - Can take up to 2 damage, then breaks.
Grants +0.25 fire rate for each half of this heart.
Replaces the boss room item in the mirror world (Downpour II / Dross II).
XP:3.5

• Coin Key - Can take 1 damage.
Can be healed by picking up coins (similarly to Keeper's health).
Spawns in shop every 2 floors for the price of 20¢
When used as a key, spends 10¢ instead of being removed.
XP:6.5

• Challenge Key - Can take 1 damage.
Heals itself after clearing 7 rooms.
Replaces the item in Boss Challenge Rooms.
XP:4

• Half-Heart Key - Can take 1 damage. (starts off empty)
Can be healed with any red hearts.
Can be filled with Rotten Hearts. Spawns 1 blue fly after clearing a room.

Spawns whenever Tainted RIsaac would get a red heart container.
Picking up another Half-Red Key will fuse them into a Red Heart Key.
XP:4.5

• Red Heart Key - Can take 2 damage.
Can be healed with any red hearts.
Can be filled with Rotten Hearts, but only takes 1 damage. Spawns 2 blue fly after clearing a room.
XP:8.5

• Bone Key - Can take 1 damage. (starts off empty)
Works identical to Half-Red Key, but cannot fuse.
Replaces Bone Hearts.
XP:3

• Eternal Key - Can block 1 hit, then breaks
+1 temporary Key Slot.
Always takes up the last slot.

The temporary Key Slot goes away if the key is broken/absorbed.
Getting another Eternal Key / Changing floors will remove the key, making the Key Slot permanent.

Replaces Heart (eternal) / spawns when Tainted RIsaac gets an Eternal Heart.
XP:7.5

• Experemental Key - Can take 2 damage, then breaks.
When changing floors / when picked up, adds a random stat up and random stat down.
When the key is removed, revert the stat changes.

+10% chance to replace a regular key for every Illness/Syringe Item Tainted RIsaac has.
XP:2.5

• Dream Key - 15% chance to block a hit.
When blocks damage, also inflicts slowness for 10 seconds to all enemies.
Spawns when RIsaac sleeps in a bed that is not in Clean Bedroom or Dirty Bedroom.
XP:1

• Awoken Key - 25% chance to block a hit.
When blocks damage, also inflicts charm for 5 seconds to all enemies.
Spawns when RIsaac sleeps in Clean Bedroom.
XP:6.75

• Nightmare Key - 25% chance to block a hit.
When blocks damage, also inflicts fear for 10 seconds to all enemies.
Spawns when RIsaac sleeps in Dirty Bedroom.
XP:6.65

• Glitched Key - Doesn't block damage.
Before taking damage, permanently turns into a random key.
Spawns in I AM ERROR rooms.
XP:0.1

• Ancient Key - Covers the first heart, blocks one hit.
When takes damage, deals massive damage in an area.
Turns into Vine Key on the next floor.
Spawns in Libraries.
XP:0

• Vine Key - Covers the first two hearts, blocks one hit.
When takes damage, deals massive damage in an area.
Turns into Blooming Key on the next floor.
Cannot be absorbed.

• Blooming Key - Covers the first three hearts, blocks up to three hits.
When takes damage, deals massive damage in an area.

When takes the last hit of damage, revives Tainted RIsaac in the previous room and spawns The Bloom miniboss in the room he died in.
Cannot be absorbed.

• Dice Key - Affects the key to the right (to the left if in the last slot).
When the affected key takes damage or gets absorbed, triggers a random dice effect.

Uses D10, D8 or D12 in hostile rooms and The D6, D20, D8, D1, Eternal D6 or Spindown Dice otherwise.

Breaks when the affected key is removed.
Has a chance to spawn in Dice Rooms and Arcades.
XP:2

• Astral Key - Affects the key to the right (to the left if in the last slot).
When the affected key breaks or gets absorbed, spawns 3 wisps related to the key.
Spawns +1 more wisp every time it triggers.

When absorbed, spawn a Quality 3 Lemegeton wisp.

Spawns in Planetaruims as a choice between the original planetarium item or Astral Key.
XP:8.5

• Skeleton Key - Can take up to 6 damage, then breaks.
XP:15

• Note Key- Can block 1 hit, then breaks.
When blocks damage, permanently charms all non-boss enemies in the room.
Drops from The Siren boss.
Cannot be absorbed.

• Cracked Key - Can take 1 damage, then breaks.
When takes damage, opens all nearby Red Rooms.
Replaces regular keys in Red Rooms.
XP:2

• Red Key- Can take up to 2 damage, then breaks.
When takes damage, opens all nearby Red Rooms.
XP:3.5

• Red Key Ring - Can take up to 3 damage, then breaks.
When takes damage, opens all nearby Red Rooms.

After taking damage, if there is still health left, will turn into Red Key.
When used as a key, turns into Red Key instead of disappearing completely.
XP:5.5

If Epiphany is installed:

• Multitool - Affects the key to the right (to the left if in the last slot).
Becomes an identical copy affected key, copying everything except the XP cost. (Loses this ability)

Cannot copy Dice Keys, Astral Keys and other Multitools.
XP:3

Open up the hidden Red Door in the Home level as RIsaac.

The following special synergies and interactions for Tainted RIsaac have been documented.

* Note that not all possible synergies and interactions are listed here.

• Download The Bimbing of AIsaac from the Steam Workshop.