Tainted Lazarus

Tainted Lazarus is a character added in The Binding of Isaac: Repentance. He is the alternate version of with living Tainted Lazarus having ragged hair and dirt, Dead Tainted Lazarus is the same but covered in blood and glassy eyes. Tainted Lazarus is unlocked by reaching and using either the  or the  to access a special room in one of the walls while playing as Lazarus.

Tainted Lazarus has two different states: Tainted Lazarus and Dead Tainted Lazarus. Tainted Lazarus starts with 3 red hearts, whereas Dead Tainted Lazarus starts with 2 soul hearts. Both characters have their own attributes, as well as their own items and trinkets. Whenever a room is cleared, including each wave of multi-wave rooms like in Greed Mode and Challenge Rooms, Tainted Lazarus swaps between the two forms, essentially requiring the player to play each character on every other room. The flipping between forms will also effectively act as a room transition for items such as. Tainted Lazarus starts with in his consumable slot, which can be used to swap state immediately.

Item Interactions

 * : Currently unimplemented.
 * : If you go down a floor while on the character not possessing the item, the Stairway will not spawn on that floor.
 * Neither character can collect souls when they are not active. This means that as soon as the room becomes cleared, all souls still in the air are lost, even after you Flip.
 * If one character has lost soul and it dies, it will respawn after that character is active again. Going to the next floor with the character that doesn't have lost soul will still grant its rewards once the character is active again.
 * will work while either form is active.
 * will only generate glitched items if the form holding it is the one to see the item first. This can allow the player to get normal, unglitched items onto the form holding TMTRAINER, and glitched items onto the form without it if desired.
 * Notably, this allows for Tainted Lazarus to obtain quest items such as or  despite holding TMTRAINER. To do this, the form WITH TMTRAINER must be the one to fight Mom, due to the Polaroid and Negative spawning slightly after Tainted Lazarus flips forms.
 * Blood Puppy Will rarely rage as it needs to get all 15 kills in the same room.
 * There's Options will only take effect if the character that holds the item is flipped to when clearing the boss room. So if dead Lazarus has the item, tainted Lazarus will need to clear the boss room in order to get the additional item pedestal.

Good Items

 * allows a second storage of Flip, allowing it to be used slightly more freely.
 * Book of the Dead: Bone orbitals and charmed Bonies spawned by Book of The Dead carry over through transforming and benefit either form of Tainted Lazarus.
 * Items like, , and other drastic health increases allow Tainted Lazarus to tank large amounts of damage in longer boss fights if spread between forms.
 * Becoming Tainted Lazarus by using Clicker can transform into him as a single character, without the Dead Tainted Lazarus pairing. This makes the run much easier, because it removes the complications the character usually has.  He still carries Flip, but using it has no effect. (Note: Quitting the game and returning to the run will fix Flip)
 * Wisps created by will remain after flipping between forms, and flipping to the form of Tainted Lazarus that is not holding the book will create a Flip wisp, even if Flip was not activated manually.
 * Large damage increases such as or  are useful to get onto Tainted Lazarus's living form early to make up for his damage deficit.
 * and allow for potential duplications of strong items to get on both forms. Though keep in mind Devil Rooms or Angel Rooms would likely require the form holding them to be active upon entry. Locate the boss room, and if necessary, clear rooms until Flip is charged and you are playing as the form NOT holding Diplopia or Crooked Penny. Upon defeating the boss, Tainted Lazarus will Flip automatically, allowing the duplication of Devil or Angel Items, followed by flipping and taking the same item on the other form.
 * is potentially Tainted Lazarus's best Item. This item acts differently for him and will take up both forms' Active Item slots, switching between the two of them on use. This effectively makes the item a one room charge Flip, allowing much more freedom with your playstyle, and if desired, focusing entirely on one form's build.
 * Having one form hold with a medium to large pool of heart containers can extend the potential time before needing to flip, extending your health bars even further.
 * can allow for more use of one form's Active Item, or just more use of Flip.
 * 's damage bonus does not decrease when the form holding it is inactive.
 * can be a good way to prevent one form from lagging behind the other power-wise.
 * Offensive Active Items that charge on a timer, especially and, can make up tremendously for one form that happens to be lagging behind. The Sharp Straw in particular, due to how it calculates damage, can make the weaker form much more offensively viable during end game boss fights.
 * In Greed Mode, if you take a hit with, flip, then flip back, the Crown of Light will be active again.
 * Old Capacitor is a great trinket to find. This will effectively turn Flip into a 12 charge item (due to only being active half of the time), however the increased spawning of Lil Batteries can allow more micromanagement to take place when a floor is finished, flipping between forms as needed.
 * Watch Battery is a good alternative, or even supplementary trinket to keep on the other form, as it increases chances of finding Lil Batteries as well.
 * Low charge Active Items with simple, effective uses, such as, , or can be recharged within one large room, and can supplement the lack of power Tainted Lazarus is prone to.

Bad Items

 * High charge Active Items tend to be too high maintenance to get much use out of on Tainted Lazarus without an alternate plan to charge them.
 * While not exactly a bad choice, extra lives like or  require a bit more thought to get use out of, due to only reviving the form holding it. If a 1up! is found, try to have the form with more heart containers pick it up to get the most use from it.
 * Any effect that only lasts for the current room, like, loses almost all use while in Greed Mode, as Tainted Lazarus will switch forms per wave. In normal and hard mode, this is only true in situations such as Challenge Rooms or Boss Rush.

Trivia

 * The achievement for unlocking Tainted Lazarus is called "The Enigma", a possible title for the character.
 * An "enigma" is commonly referred to as "a person or thing that is mysterious, puzzling, or difficult to understand."