The Lost (Strategy)

has no health, dying by any damage taken. Therefore, he needs to be played with extreme care. Although possible, it is extremely difficult to finish a full playthrough without getting hit at all. Powerful item combinations are often necessary for a successful run.

General Tips

 * Before attempting runs with The Lost, unlock any items that may be helpful for The Lost.
 * It is absolutely suggested to unlock The Lost's intrinsic greatly lowering the difficulty of his usage. This can be done by donating 879 to the Greed Machine.
 * It is recommended to have advanced knowledge of all types of rooms, champions, and enemies.
 * The Lost's ability to fly can be used to hide safely above obstacles and pits, avoiding enemies and projectile contact.
 * Always play on hard mode, as hard mode is required to unlock . If the player manages to get good item combinations, the difficulty will not matter much.
 * Bombs can be used to escape rooms you think you cannot handle.
 * The Lost will absorb soul, black, and Eternal Hearts by picking them up, but will not gain any health from them. It is recommended to avoid picking them up in case the, a Dice Room (with 3 pips, 2 if the hearts spawn in the Dice Room), or a is found later on.
 * The same applies to useless items (except while holding the, that can reroll the passive items). If an option to reroll items is found, they can be changed if not yet picked up.
 * Three orbitals of any kind absorb nearly all projectiles. It is recommended to use Slot Machines as much as possible to obtain Pretty Flies.
 * The Lost does not receive Bad Trip or Health Down pills. This makes pills more useful since they are more likely to have positive effects.
 * With the Missing Poster, a run may be taken to the end with an easier character and finished as The Lost by dying on purpose, granting the unlock for The Lost without doing a full run.
 * Since The Lost does not take damage from the Greed Mode button, you can dramatically limit the number of enemies you have to face at a given time by stepping back onto the button after activating it.

"The Still Statue"
This strategy is very safe and easily played. It combines with any automatically damaging familiar. This allows The Lost to enter a room, become invulnerable, and let its familiar clear the room. There are almost no rooms where The Lost gets hit before it enters statue form. This strategy requires a lot of patience.

Although many familiars are not able to clear all types of enemies or rooms, it is still recommended to get any type of familiar the player finds. Some examples are:
 * : Extremely powerful, as the harbingers will travel anywhere across a room that spawns locusts and leaving trails of creep. The War and Death harbingers will also chase enemies.
 * : Extremely powerful, because it reaches any enemy and will eventually clear the room against any type of hostiles.
 * and : Reliably take out enemies nearby, but will not target foes far away.
 * : Can chase after enemies like Lil Haunt, but due to its poor programming, it often gets stuck, causing you to have to move to kill an enemy. It is also unable to pass over pits.
 * : While not as powerful as Daddy Longlegs, it's one of the few familiars that chase enemies (and don't require you to take damage to summon).
 * : Still dealing damages when is active, maybe useless against bosses who stay away from The Lost.
 * Orbitals: Provide decent damage against chasing enemies, but are useless against enemies that stay on distance.
 * : It reaches any spot of a room and will be able to take out most enemies. A lot of time is required, though.
 * : Shoots only horizontal and vertical, not reaching enemies that stay diagonally. Robo-Baby 2.0 will still clear most rooms. If Robo-Baby 2.0 is moved, a statue form will be exited.
 * and : Blue Flies and Spiders target most enemies inside a room. The flies may not attack foes far away, the spiders are unable to pass over pits.
 * : Similar to The Peeper, but with a much larger area of effect. Still has trouble with large rooms, however.
 * : Similar to Midas' Touch, enemies that touch The Lost when is active will be poisoned, but is useless against foes and bosses who stay away from The Lost.

Issues
Although the strategy is quite safe, game-ending issues likely occur. Some example scenarios are: It is required to have an emergency option if a room cannot be cleared as intended in such scenarios. Spacebar items, cards and pills can be safely activated, even if The Lost in statue form currently has enemy contact. Another option is to exit the run and reenter it by pressing the continue button. This will place the player at the start of the room but all monsters killed would have to be killed again if the player did not clear the room first.
 * The Lost fights Loki with a Poky inside the room. The boss will always stay at distance, making familiars like useless. Poky pushes constantly against The Lost, forcing him not to move.
 * The Lost fights a room full of Mask + Heart, the Hearts being behind a pit. Familiars like Leech are useless, while The Lost is constantly attacked by a Mask.
 * The Lost fights Globins, while his follower is not doing enough damage to finish them off after they fell into goo. One Globin is always alive at a time and attacking The Lost.

Boss Rush
The method may be perfect for the Boss Rush fight itself, however, the player will probably be progressing too slow, not finishing Mom in time. Therefore this method is not recommended to attain the Boss Rush.

Execution
The game is restarted until is found in a treasure room adjacent to spawn. Then, the player has to rely on finding proper familiars later on.

"Getting Carried"
This strategy is very general, though leading often to success. The goal is to gain a massive offensive potential, killing enemies before they can hurt The Lost. To survive game-ending mistakes, The Lost also tries to find shielding, invulnerability or reviving items. The strategy bases a lot on item luck because some of the most powerful items in the game need to be found early on.

Key Items

 * Offensive
 * : Grants massive power, is piercing and spectral, can be charged in the preceding room and instantly fired.
 * : Shoots a giant damaging tear with no downside.
 * : Offers massive damage, is piercing and spectral.
 * Increases tear damage more than most other items. If combined with other damage increasing items, it makes most enemies in the first chapters one-shot and shortens boss fights significantly.
 * The Guppy transformation increases the Lost's offensive potential significantly, and several of the items required for it are useful to the Lost in their own rights.

The goal is to obtain at least one offensive and one defensive item early in the run, additional ones later on. If they are combined with further helpful items, a run becomes very promising.
 * Defensive
 * : Gives The Lost nine lives.
 * : Absorbs the first hit in each room, nullifying a game-ending mistake once per room. It also allows the Lost to enter Curse Rooms and open Spiked Chests and Mimic Chests.
 * Care must still be taken when making use of curse rooms, as any damage taken inside of it will nullify the Holy Mantle charge, trapping the Lost inside unless he has some way to generate a shield, teleport out, or extra lives.
 * The Holy Mantle as a starting item can be unlocked by donating 879 coins to the Greed Machine.
 * ,, and : Have a chance of deflecting projectiles that come into contact with the Lost.
 * Also, will also make the Lost immune to explosions and stomp attacks, increasing his survivability further and allowing safer use of items like  and.
 * Destroys bullets upon contact with tears. It makes "bullet-hell" boss fights like It Lives significantly easier.

''Note: and  are also major offensive key items. However, it is assumed the player has not yet unlocked Godhead. Sacred Heart can earliest be found on the third floor with very low chances, is therefore not mentioned.''

Issues

 * Although you can restart a game until you find a key item in the first treasure room, you are still dependent on item luck later in the run.
 * Many key items are special items, lowering the chances of finding such combinations.
 * Running only with key items may not be enough, therefore additional damage ups or emergency options may be necessary.

Boss Rush
This method is well suited for the Boss Rush because The Lost can progress quite fast with his massive damage output. The Boss Rush fight itself shall be done with extreme care because many defensive Items lose most of their value in a long fight:
 * would revive you outside, ruining the attempt.
 * will still trigger once in the Boss Rush fight, but that may not be enough for the whole duration of the fight.

Execution
The game is restarted until one of the key items is found in a Treasure Room adjacent to spawn. Afterward, the player has to rely on finding additional key items and synergies later on.

Note that can only be found in Devil Rooms, and  only in Curse Rooms, Devil Rooms and Red Chests. The player may decide if they want to check on these opportunities or rather restart instantly.

Some players enter a Curse Room if it is located adjacent to the start. This will usually be fatal. Rarely, though, a can be found in it. This behavior can make sense, as the run would anyway have gotten restarted without a Treasure Room next to the spawn.

"Remote Control"
This method bases around any remotely controlled damage source, such as, , or. After entering a room, The Lost tries to find a safe hiding spot as soon as possible, like above an obstacle. After being safe, he uses his remote damage source to finish the room. Acquiring both and  can help immensely, especially during the fights against Isaac and ???, as the tear can easily block all enemy shots. Acquiring and  can also be very helpful as enemies can be pulled away from The Lost.

Issues

 * Many rooms do not contain any safe spot, quickly making the method counterproductive.
 * Flying enemies can reach any spot in the room. Jumping enemies like Hoppers can also jump over obstacles if they find a landing spot behind.
 * prevents The Lost from firing normal tears, which may be fatal in rooms without hiding places.
 * The player may focus on their controlled tear/familiar, rather than watching The Lost, overlooking a deadly danger.

Boss Rush
If the player manages to reach the Boss Rush room, their odds are quite good. The Boss Rush room offers some rocks as hiding spots, and many bosses stay quite calm. This allows for a nice damage output with the remotely controlled familiars. Flying, fast or mobile bosses, like Fistula, may still become problematic, and therefore treated with extreme care. Also, the variety of Brimstone and explosive attacks are very dangerous. There is a bug who will give the player the "Boss rush completed" achievement and will unlock the D100 without actually completing the boss rush. To make this, the player needs some bombs before entering the boss rush. Once the player is inside, he should place bombs in all the skulls he can find, until an enemy spawns from one of them. If the player kills the enemy (Without picking up any of the boss rush items) the game will think the room is "cleared" and give the player the achievement.

Execution
The game is restarted until one of the above items is found in a Treasure Room adjacent to spawn.

Emergency Options
The Lost should always be prepared for the unexpected by having an emergency option.

Note: and  allow a much more flexible use of spacebar items and are generally recommended.

Shield and Invulnerability
Becoming invulnerable is often avoiding deadly situations, therefore having such a card or spacebar item is highly recommended.


 * Algiz offers a shield for 30 seconds 20 seconds. Combined with the Clear Rune, it forms one of the best defensive item combinations.
 * offers a shield for 10 seconds.
 * fears all enemies, deals contact damage and offers invulnerability for five seconds.
 * and grant invulnerability and contact damage for five seconds.  has a similar effect, but is not completely controllable.
 * grants a 5-second invulnerability, letting The Lost reposition himself safely. It comes with only one charge, thus can be used often.

Teleport
Teleportation can be used to avoid run-ending situations by just leaving the room on demand. However, depending on the method used and on the floor the item is used, the player may end up in a random, more dangerous room. Teleporting into a Curse Room can potentially end a run, as under normal conditions they cannot be exited without taking damage. There is also a chance of landing in the I AM ERROR room, which forces the player to leave items and pickups behind and potentially forces the player to skip an unlock.


 * Any card providing teleportation, optionally combined with.
 * Broken Remote
 * If combined with a no-cooldown spacebar item, such as How to Jump, it provides infinite teleportation.
 * Telepills
 * Door Stop
 * Allows you to walk out of any room.
 * Door Stop
 * Allows you to walk out of any room.

Hard Removal
Hard Removal describes the option to clear a dangerous room instantaneously on demand. Items offering hard removal are:
 * kills any enemy in its path, including bosses (not including Delirium), in one hit. It is very useful for single-targets but doesn't have the area of effect for massive enemy horde rooms.
 * clears a room instantly, but doesn't work against bosses, except Brownie, Clog, Dingle, and Dangle.
 * deals massive damage in a cross-pattern, killing all non-boss enemies in its path, and severely damaging bosses.
 * can clear a whole room extremely fast if the item is spammed, the damage is high enough and if enough coins are available.
 * and kill most non-boss enemies in a room.

Resurrection Items
These items do still work with The Lost, although the life number does not appear on the HUD. They give the player another chance if a fatal mistake was made.
 * offers one life.
 * offers nine lives.
 * has a 50% chance of reviving The Lost.
 * When combined with Dead Cat, Guppy's Collar takes priority over it, potentially granting more lives.

Angel & Devil Rooms
Devil and Angel Rooms appear quite frequently to The Lost because he is not allowed to take damage. The Lost can take Devil deals for free. However, Angel Rooms offer some of the most helpful items for The Lost.

The Lost can only choose one of the available Devil deals.

It is generally recommended to go for Devil deals, and thus hinder Angel Rooms to appear, though the player is free to pursue Angel Rooms if they find them more attractive. is a strong item to obtain early as it will ensure that The Lost can visit a Devil or Angel Room on every floor except for Basement/Cellar I and everything past The Womb/Utero II. fulfills a similar effect, however, another spacebar item may be preferred.

Devil Room
Although the Devil Room may only contain Black Hearts or Red Chests that only contain Soul Hearts, Troll Bombs or enemy spiders, it usually has helpful items, though some such as or  can be either useless or dangerous. Some of the most valuable are: For a full list of Devil Room items see Devil Room item pool.
 * All items required for Guppy, especially (Note: Red Chests can also contain Guppy items)
 * Many damage ups
 * Items granting fear tears
 * All items required for Guppy, especially (Note: Red Chests can also contain Guppy items)
 * Many damage ups
 * Items granting fear tears
 * Many damage ups
 * Items granting fear tears

Angel Room
The Angel Room often contains Soul or Eternal Hearts, being useless for the Lost. Many items that can be obtained are of no use, too, such as or, and some such as  or  can actually be dangerous. However, with luck, one may find a very valuable item, such as: For all Angel Room items see Angel Room item pool.
 * (gives The Lost a use for soul and black hearts)
 * (if the player has already defeated Satan as The Lost)
 * (if the player has already defeated The Lamb as The Lost)
 * (if the player has already defeated Hush as The Lost)
 * (gives The Lost a use for soul and black hearts)
 * (if the player has already defeated Satan as The Lost)
 * (if the player has already defeated The Lamb as The Lost)
 * (if the player has already defeated Hush as The Lost)
 * (if the player has already defeated The Lamb as The Lost)
 * (if the player has already defeated Hush as The Lost)

Positive Items
Aside from the already mentioned items, the following are of great use:
 * Any item increasing damage in some way and/or any other of The Lost's stats.
 * The, unlocked by donating 999 coins to the Donation Machine slows down all enemies in the room, all projectiles, and makes enemies that charge for an attack charge forward very slowly.
 * The Stopwatch was nerfed to only work upon taking damage, although, in a recent update, it now works when the Holy Mantle's shield is depleted.
 * Although not as powerful as before, Stopwatch still slows everything down to a great degree, allowing more room for error.
 * is similarly beneficial like itself.
 * Items that inflict crowd control status effects such as fear, slow or petrification can be useful. On the other hand, some players dislike these items because they can make enemies move in unpredictable ways.
 * removes curses.
 * The 's properties make it one of the most useful items for defeating the waves of mobs and bosses in Greed Mode. Filling the room with flames before pushing the button to start a new wave, although very time consuming, virtually guarantees a swift victory with very little risk.
 * ,, or can reroll negative or useless items into something useful, while can do the same with pickups.  acts like the three combined.
 * The D4 and the can deactivate very important items you obtained earlier.
 * As the Lost starts with the Holy Mantle after giving the Greed Machine 879 coins, the D4 can potentially be deprecated from the start.
 * If is unlocked, the starting Holy Mantle won't be rerolled while using D4, D100, or anything with similar effect.
 * After multiple re-rolls, the D4 and D100 can be counterproductive. If the item pools are depleted, they will only give The Lost.
 * and increase the chances of the Lost finding useful items.
 * grants immunity to explosions, making it especially useful should the player have explosive items such as or.
 * Items revealing the map are very useful to avoid unnecessary rooms.
 * is always active.
 * is essentially a permanent double damage as it cannot be deactivated.
 * can greatly increase The Lost's damage output without any negative effects.
 * Missing Poster effectively acts as a 1-Up on The Lost.
 * is always active for The Lost. The Lost will not benefit from the flight given but will benefit from the periodic invincibility it grants.
 * Safety Scissors neutralizes the threat of Troll Bombs and grants additional bomb pickups.
 * can convert health ups or otherwise useless items into stat boosts.
 * allow player to reroll useless item into better/more usable ones, as losing items such as isn't as significant.
 * Apple of Sodom converts useless red hearts into blue spiders.
 * Despite red heart-dropping items being useless, they can be used in synergy with this item to farm for blue spiders.
 * Perfection is essentially a free +10 Luck, as taking any damage results in death, making the loss of Perfection a non-issue. This can synergize with many Luck-based items:
 * At 9+ Luck, all tears are replaced with teeth, essentially giving a 3.2x damage multiplier.
 * or : At 11+ Luck, The Lost is guaranteed to shoot fires, which effectively damage enemies and block enemy projectiles.
 * has no downside for The Lost, generating free items with no loss of durability or risk of death.
 * allows to remove useless item from item pool similar to, but still allows the player to find strong defensive items like.
 * helps greatly with protecting The Lost from bullets, making bullet-heavy bosses like Hush and Mother much more bearable.
 * ' downside becomes a non-issue since any damage taken by The Lost will kill him anyways, essentially giving double the items at no cost.
 * stays at maximum level as taking damage would kill the Lost anyways (unless it has extra lives).

Useless Items
The following list includes items and trinkets that only affect health, only grant flight, only grant spectral tears, use damage as a trigger or contain a combination of what's listed with no other positive effect. It's advised to pick them after a floor has been explored in case a, , or a Dice Room (with 1 or 6 dots) are found later on during the run.

Notes on item selection
 * ,, and are not included because while they do not provide any passive benefit, they do count for transformations.
 * Listed items that generate heart pickups of any kind are useless in most scenarios, but can be converted to other types of pickups if The Lost is holding the or.
 * will increase damage if The Lost has multiple lives.
 * Items that activate a -like effect upon getting hit have a very limited use, as they can deal the last bit of damage needed to kill a boss, or clear a room if The Lost has multiple lives.
 * is mostly useless, but not completely, as it raises the chance of finding.
 * Rosary now gives a tears up as well, making it more useful.
 * Missing Poster is no longer useless for the Lost.
 * , and  are useless in Afterbirth because The Lost now starts with spectral tears. They are still useful items in Rebirth.
 * Blind Rage is only useless if the player has not unlocked as The Lost's starting item.
 * Items that increase your chances of finding Soul Hearts or Black Hearts gain some use when combined with.

Negative items

 * , Broken Ankh, and  grant extra lives but respawn The Lost as, , or  respectively, which will cause the game to treat them as these characters instead of The Lost. It is suggested to avoid these three items altogether if the player is interested in gaining The Lost exclusive achievements and/or completion marks.
 * no longer maintains its main benefit of providing Soul Hearts as Soul Hearts are now useless. While it may spawn a friendly spider, it is also likely to spawn an enemy spider, which can instantly kill The Lost if the player is not careful.
 * Dark Bum now has a 20% chance to spawn a random pill, card or rune, making it slightly more useful for The Lost.
 * With, Dark Bum will be useful to convert useless Red Hearts to useful Soul Hearts. However, the player must still be careful of Spiders.
 * , while having many useful synergies as well as the added benefit of immunity to Brimstone lasers, makes dodging more difficult in many scenarios, leading many players to take damage when they otherwise would not have. It is also very difficult to avoid a stray laser from an Eye, as The Lost cannot block this shot and protect Isaac's Heart from it. Also, there is a chance it can spawn atop an Eye in the It Lives fight, leading to a very cheap and unavoidable death.
 * Any explosive items, such as, , or should be used with extreme care.
 * If the player chooses to pick up, they should not pick up or , as an unexpected shot against a wall will lead to instant death.  is also problematic as it can cause explosions to happen in closer proximity to the player than desired.
 * Items that work by causing self-damage, such as the, or  will end the run if used and must be avoided.  also has the potential to prematurely end a run if a self-damaging item is triggered.  will allow The Lost to use these items without taking damage.
 * reduces speed by 0.2 and does not provide any benefit.
 * will replace all room clear and champion drops with soul hearts, resulting in much less pickups throughout the run.
 * and are not great as they remove The Lost's ability to use obstacles to his advantage, as they can break these obstacles. Also, stepping on a poisonous mushroom, or carelessly stepping on a Bomb Rock can end a run. The only benefit is the small chance of finding a trapdoor or items like  or  when breaking said obstacles.
 * : Unpredictably pulls enemies towards The Lost, especially floating enemies like Boom Flies. It's advised to avoid this item unless The Lost has, as both items combined may create a powerful synergy.
 * Strange Attractor now pulls enemies towards where the magnetic tear lands, making it safer to take.
 * may seem useful because it doubles your damage, but it requires you to get closer to enemies, resulting in you being more likely to get hit.
 * / Orbitals nullify this a bit, but you still have to get close to enemies.

Seeds
Note that seeded runs do not count towards achievements or unlocks. 4BGT 79XL (Hard) ("Getting Carried" Strategy: Brimstone in the first Devil Room. After obtaining it, Forget Me Now shall be used to get Holy Mantle in the Treasure Room in Basement I. Infamy is found in Necropolis II. Lost Contact will be in the Secret Room in Utero I, Dead Cat in the Super Secret Room and Goat Head in the Dice Room.)