Tainted Lost

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

Tainted Lost is just like The Lost but instead of, it starts with a and does not start with the. Tainted Lost has flight and spectral tears, but no health and dies from any damage taken. It also starts with a 1.3x damage multiplier, giving it higher starting damage and a higher efficacy for damage-increasing items. Cards and Runes have a 10% chance of being turned into a.

Beating Delirium with is not required for Tainted Lost to obtain the.

As with The Lost, Devil Room items and Black Market items can be taken for free but will be presented as a choice. Taking one item will cause the others in the room to disappear.

Item Exclusion
Tainted Lost has two mechanics that determine what items it can encounter.

Offensive items
The first mechanic makes it so that any items that are not tagged "offensive" cannot be naturally encountered while playing as Tainted Lost. This disallows items that it can't take advantage of, similar to 's, but it also prevents many powerful defensive items, such as and , from naturally spawning. These items will be rerolled, and items that are set drops from mini-bosses (ex. Super Pride dropping ) will never be dropped. Even will skip over disallowed items as they are generated.

Disallowed items can only appear by using or as set drops from props (ex.  from a skull).

Not all items tagged "offensive" are particularly offense-oriented items. Examples of this include and.

Item quality
The second mechanic uses the item quality system. Items with a quality value of 2 or less have a 20% chance of being rerolled when encountered as Tainted Lost.

Excluded Items
The following items cannot be found while playing as Tainted Lost.

Strategy
With only a single for defense, defensive items become just as important as offensive ones, as you won't be able to afford taking more than a single hit the entire run unless you find another Holy Card. However, because all items not marked as "offensive" will automatically be rerolled, defensive options available are less plentiful.

A good way to secure a powerful run is to visit as many Boss Challenge Rooms as possible. It is possible for the player to use the alternate floors to their advantage by sticking to the second floor of each chapter. By visiting II /  II, the player can also get an extra boss item from the Mirrored World. This strategy comes with the added risk of having to fight more bosses, but provides the potential to snowball the players stats and make later floors much easier to survive in.

Good Items

 * Ace of Spades: Chance of changing the room drop reward to a card, and chance of getting a card as additional rewards from certain things, indirectly increasing the chance of getting a Holy Card.
 * : Grants an extra life, respawning in the same room and damaging nearby enemies.
 * : Allows reuse of the Holy Card.
 * Endless Nameless: Has a 25% chance to spawn another Holy Card when one is used.
 * : One-time Holy Mantle for boss battles.
 * Blanket does not currently work in Greed/Greedier Mode when fighting boss battles.
 * Especially useful against enemies that spawn bullets or other enemies on death as they will often be instantly blocked or damaged/killed, respectively.
 * : Very powerful in combination with Panic Button, and allows infinite invincibility when fighting most endgame bosses if the player holds.
 * : The Bone orbitals spawned from this item can block projectiles, greatly increasing survivability,
 * and Lemegeton: Rings of wisps can block a lot of projectiles.
 * : Deletes enemy shots at random, which can make surviving bullet based enemies easier. This is in addition to the item slowing down enemies and providing extra consumables.
 * : Allows Lost to be invisible upon entering a room and plan out their first attack.
 * : Slows projectiles to make them easier to dodge.
 * : Can be used with.
 * becoming Tainted Lost by using Clicker allows Tainted Lost to keep all previously collected items. This allows many useful defensive items that Tainted Lost normally can't collect.
 * : Allows an extra item to be taken from devil deals.
 * : The downside of the item is inconsequential due to Tainted Lost's lack of health.
 * / /Dice Bag: Allows duplicating Holy Cards.
 * : Freezes enemies that are about to touch the player.
 * : The downside of the item is inconsequential due to Tainted Lost's lack of health.
 * : Allows more chances of Holy Cards.
 * : Allows every consumable to be a Holy Card if one is used after obtaining.
 * Flat File: Allows free Curse Room entrance.
 * / : On-demand invincibility with contact damage.
 * Any luck-based tear effect such as, , , and  benefits well from Perfection. One of the most powerful tear effect among them is : at 11 luck, every tear is accompanied by a blue spectral flame that deals heavy damage and blocks enemy projectiles.
 * : High damage shots that allow to remove especially dangerous enemies fast. The downside of the item is inconsequential due to Tainted Lost's lack of health.
 * : Allows recovery of a Holy Card shield.
 * Consuming Glowing Hour Glass with will result in a Void that doesn't lose its charges when activated, making it possible to repeat this process over and over.
 * can increase the amount of golden chests found in a run, and hence allows more chance of holy cards.
 * : Blocks projectiles.
 * : Can be safely used to generate items with no loss of durability or risk of death.
 * and Door Stop: Most rooms can be checked for a safe plan of attack, or bypassed entirely.
 * Missing Poster: Allows a one-time revive upon death, respawning Tainted Lost in the previous room.
 * : Lost's lack of health makes it always stay at maximum level.
 * : Can be used with a damaging orbital such as, or to get lots of damage on bosses for free.
 * Perfection: 10 luck with no downside, as Lost dies anyway if you get hit.
 * : Protective pills like Power Pill or Feels Like I'm Walking on Sunshine may be helpful.
 * : Smaller size makes you harder to hit.
 * : Blocks many projectiles from hitting Lost.
 * : Allows Tainted Lost to obtain items otherwise hardcoded to not spawn for him.
 * Some incredibly useful Reroll chains for Tainted Lost include:
 * to
 * to
 * to
 * to
 * to
 * to
 * to to
 * to
 * to to
 * to
 * to
 * to to  to
 * to to  to
 * : Increases the chances of finding Holy Cards, and allows pill-generating items to spawn Holy Cards.
 * : Slight projectile reflection aura makes it easier to dodge things.
 * : Creates a ladder to an Angel Room shop at the start of every floor, with the shop potentially selling powerful Angel Room Item Pool items and Holy Cards.
 * : Can be used to block projectiles or enemies.
 * : Timed invincibility allows exiting Curse Rooms safely.
 * Wooden Cross: A single-use Holy Mantle per floor. Note that it does not stack with Holy Card; it is thus wise to save Holy Cards for when the shield from the Wooden Cross is broken.

Trivia

 * While items like, and  are not considered items that the Tainted Lost can find, they will still appear for him if the conditions for finding them are met.
 * The achievement for unlocking Tainted Lost is "The Baleful", a possible title for the character.
 * "Baleful" means "ominous" or "harmful or malignant in intend or effect", possibly referring to how Tainted Lost has higher base damage than his regular counterpart and can find better items.
 * and can still be found while playing Tainted Lost, despite both items being useless for the character.