How to Unlock Tainted Characters in Binding of Isaac

In The Binding of Isaac: Repentance, you have access to a sizeable cast, but there are also Tainted versions of these characters. Tainted characters have a different appearance and get new items and abilities. However, you have to unlock them first.

Thankfully, all Tainted characters are unlocked practically the same way. There are two items you can use to unlock them, but both achieve the same effect. Keep on reading to find out the unlocking process for Tainted characters.

How to Unlock Tainted Characters

Depending on what you want to do, you’ll need to obtain a Red Key or Cracked Key. The Red Key is for unlocking Tainted Isaac, but it only appears once. Fortunately, you can gain Cracked Keys in future runs to unlock the Tainted versions of other characters.

Next, we’ll take a look at a few things to do before unlocking all Tainted characters.

Defeat Mother

Defeating Mother at least once is crucial to unlocking the Tainted characters. You can find her in the Corpse II biome. She’s the Repentance DLC’s new boss.

Locate Dad’s Note

In another run, you need to head to the Depths II biome to find Dad’s Note. Here are the steps:

1. The boss will be in a room. After defeating him, you have to exit the room via teleportation.
   
2. Return to the starting room and find a door.
   
3. Unlock it with The Polaroid, The Negative, or the Faded Polaroid.
   
4. Get Dad’s Note and start the ascension.

If you don’t have teleportation, you can use this trick.

1. Go around the level and check all the skulls.
   
2. Find a skull that looks different from the others.
   
3. Bomb it to obtain the Fool card.
   
4. Use the Fool card to teleport away.
   

Reach the Home Area

The Home area isn’t randomized, meaning everyone will pass the same rooms. Clear them, and you’ll find the Red Key. Here’s a breakdown of the steps:

1. Proceed with the ascension and reach the Home area.
   
2. Go through the rooms until you reach Mom’s Room.
   
3. Open the chest inside Mom’s Room.
   
4. Get the Red Key.
   

Use the Red Key

Now, it’s time to unlock the Tainted character. The character you’re playing as will determine which Tainted character you get after using the Red Key. For example, you unlock Tainted Isaac if you were playing as Isaac.

1. Exit Mom’s Room to the hall.
   
2. Use the Red Key.
   
3. A hidden room will appear, and you have to go inside.
   
4. Touch the Tainted version of the current character you’re playing.
   
5. You’ve officially unlocked the Tainted character for new runs.
   

Cracked Key

After unlocking a Tainted character for the first time, the Red Key won’t be in Mom’s Room anymore. While you can still find Red Keys in Curse Rooms, getting them from Key Masters, Red Chests, or Secret Room, there’s an alternative. The Cracked Key is far easier to obtain than another Red Key.

Here’s how to get a Cracked Key:

1. Go to a boss room or treasure room.
   
2. Drop any trinket item you’re holding.
   
3. Find Dad’s Note again.
   
4. During the ascension, you’ll eventually come back to all the boss rooms you visited before.
   
5. Once you come back, the trinket will become a Cracked Key.
   

After this, you only have to go to the Home area again and use it the same way as the Red Key. You can unlock all other Tainted characters using the same process.

The Keys to Success

Red Keys and Cracked Keys help you unlock all Tainted characters, though we recommend sticking to the Cracked Keys later on. With this knowledge, you’ll unlock all 17 of them in due time. All of them have unique playstyles from their original counterparts, so it may be worth your while to unlock them all.

How long did it take for you to unlock Tainted characters? Who’s your favorite one to play as? Tell us in the comments section below.