Overview
I will try my best to info you about the bosses of the game.
The Basement
The Duke of Flies
Behavior
The Duke coughs out regular Flies and Attack Flies around him and floats around the screen in random directions, while bouncing off of walls. He takes a large amount of knockback from Isaac’s tears.
The Duke coughs out regular flies for defense and will keep doing so if you continue destroying them. These flies will circle around him. If he has too many flies around him, he can blow them away at high speeds, which will cause them to follow Isaac.
Once he has sufficient defensive flies, he will proceed to spawn attack flies instead, which are stronger and poised to attack the player from the start.
Strategies
Actually getting your shots through to him is the most challenging part of this encounter, and that can be accomplished in a few main ways:
Firing through the gaps in his shield will make it easier to kill him.
A single Bomb will clear out most of the flies, and deal a very large amount of damage to him.
The boss gets significantly harder if you can’t land your shots right away. The green champion variation is particularly dangerous as shooting down Moters will make it very easy to get hit.
When the Duke starts spitting up Large Attack Flies, focus on them when they appear to keep things under control.
If you get swarmed by his Flies, it is always a good idea to leave the Duke alone and concentrate on his spawns. While this will not damage the Duke in any way, ignoring the flies for too long can lead to so many of them that they become too much to handle.
Having Skatole will grant immunity against all flies that are not orbiting the Duke. Attack flies that have been spawned by the Duke but not yet released from his orbit will harm Isaac if he runs into them.
Notes
The Duke of Flies has three distinct sounds that he uses before an attack. Learning what these are will help when fighting him.
One sound for spawning Black Flies.
One sound for spawning Attack Flies.
One sound for releasing some defensive flies to attack Isaac.
Champion Varieties
Orange
Green
Gemini
Behavior
The larger of the two will walk towards Isaac, trying to deal contact damage. Eventually, he starts charging with increased speed for a few seconds. Right after charging, he runs out of breath and has to stop, leaving him vulnerable to attack. The smaller one drifts along at a distance, and will fire fast-moving blood shots at Isaac if he comes near and isn’t behind cover. The umbilical cord acts like an elastic tether, keeping them in roughly the same area while not restricting range of movement too much.
Killing the larger twin will cause the smaller one to become enraged, abandoning ranged attacks in favor of charging at Isaac (if you deliberately focus-fire the small one from the start, it will be killed and you only have to focus on the big one, whose behavior will not change). While enraged, the smaller twin takes a lot more knockback, which can be troublesome if care is not taken.
Strategies
Your best option for handling these two is to run around the edges of the room, firing behind you as you go. Gemini’s speed is usually not sufficient to reach Isaac, making him easy to fight.
Movement-controlling items like Mom’s Bra and Mom’s Pad can be helpful if you find yourself unable to stay ahead of the larger twin’s frequent charges. Strong explosive attacks like Bombs are easy to land when the large twin stops for breath.
Champion Variants
Green
Gemini starts off with the two detached; however, the smaller one will act as normal. If enraged by the death of the larger one, it does not move as fast as the normal one. However, there is a chance where just the smaller half of him is green. In this case, it’s easier on the player, as when it starts its charge, it’ll move slower towards the player and is much less of a threat.
Eternal
Gemini starts out with two of the smaller twins attached. The first twin comes off when the larger third of Gemini is at half health, and the second comes off when the larger third is slain. While the smaller twins are still attached, they regenerate health, and shoot a spread of three tears.
Blue
Monstro
Behavior
He will semi-randomly switch between hopping towards the player, spitting a burst of blood shots (signalled by smiling), or launch into the air and land at the spot the player was standing in when he went up along with blood shots fired in many directions when he hits the ground.
The distance between Isaac and Monstro will not influence the attack he will choose, he switches between them at will. Therefore, you’ll want to stay at medium range to retain maximum flexibility. The blood shot spray looks nasty, but the shots have arcs that often go over your head.
It’s also possible to circle around Monstro while staying at a short distance. This way, you don’t have to worry about his shots, but his small leaps become a bit more dangerous.
Despite his bulk, Monstro moves around a fair bit; area of effect items (like Mr. Boom, Lemon Mishap, or Doctor’s Remote) will not be very effective unless you get lucky on placement. Doctor’s Remote, however, works somewhat well as you can use mouse clicks to stay on target with Monstro. Try to wait until he launches into the air, then move and aim where you were standing when he lept. Use his shadow to track where he will land.
Regular bombs take large chunks out of his health, but if he decides to launch you may end up wasting the bomb. An easy way to use area of effect items is when Monstro makes a huge jump, he will land approximately at your last position before he jumped, so just use the item before moving.
If you’re down to one heart, avoiding damage becomes a number-one priority as some of his shots (the bigger ones) can deal up to a full heart of damage.
For some people it’s hard to tell where he is when jumping in the air, so homing shots can help to predict his landing. You can sometimes tell by the shadow that his body makes in where he will land, but mainly, he only lands where your current position was/is
It’s possible to run underneath Monstro while he is “hopping”. This can make shooting a bit easier.
Pay attention. If Monstro uses his blood spray while you are cornered, look for an opening. There’s an opening in every barrage he throws at you, so use this to your advantage.
Champion Variants
Red
This version is much smaller and has less health. An additional Monstro shows up, and you’ll have to battle both of them simultaneously. In boss rooms, there will be two and in normal rooms in later levels, one will be added to the amount that would spawn in the room by default. Obviously, when smaller, it’s harder to stay still and maintain fire, and with two or three of them present, it’s best to run in a circle around them and never fully stop moving unless they’re both just hopping around.
Grey
This champion is slightly larger and has more health. He can’t launch himself into the air, and uses his shot attacks much more often.
Eternal
Appears during hardmode, Monstro vomit lasts longer, shooting more disorganized projectiles. Splits into two.
The Basement part 2
Larry Jr.
Behavior
Larry Jr. has an erratic movement pattern as he appears to ignore Isaac until the player walks directly into his path, similar to the Charger Maggot – which is also similar to Larry in appearance.
Larry Jr. has multiple segments, each that have to be destroyed to kill the boss. Destroying the head will cause the previous segment to become a head, and so on until all of the segments are destroyed. A segment that is not connected to any other segments (due to the middle segment being destroyed) will die instantly, which makes the fight easier for characters with low damage.
Strategies
Upgrades such as Cupid’s Arrow or Technology that add piercing to Isaac’s tears make the fight much easier, as all of the segments take damage.
This also applies to all items with explosive potential, such as IPECAC, which will almost always one-shot Larry Jr. if timed well.
Poison is also very effective, as each segment of his body is poisoned individually. Poisoning multiple segments essentially stacks the poison effect, dealing a lot of damage relatively quickly.
In later Chapters, Larry Jr. can appear in normal rooms a mini-boss, usually with less segments.
Using the Death Tarot Card/Necronomicon will kill Larry Jr. instantly, as each of the segments are separately damaged.
When fighting Larry Jr. while having the Bloody Lust item, destroying each Larry’s piece counts as a kill for Bloody Lust.
Champion Variants
Green
Blue
Mini-Boss Version
Larry Jr. sometimes shows up in other rooms later in the game starting from The Caves up to The Womb. He can appear in groups of three or more, and in its green or blue champion variants. The more Larry Jr.’s appear in the same room, the shorter each one of them is.
Steven
Steven is in all manners the same as Gemini, with only a couple of minor differences:
The smaller part of Steven fires shots much more aggressively and is directly bound to the bigger part of Steven instead of via an umbilical cord.
After taking about a third of its life, the smaller part of Steven will separate from the bigger part of Steven to chase Isaac independently at high speed.
Upon death, each Steven will explode into several high speed shots, similar to a Red Boom Fly, but much faster.
Strategies
The same tactics that work on Gemini will work on Steven, only care needs to be used to avoid the more rapid rate of shots. Upon the split, the player must be careful not to run into one Steven while trying to avoid the other.
Steven drops one of two items, Little Steve, a familiar with homing shots, or Steven (item), increasing damage and causing Isaac to grow a tumor with a face on his head. If the player already has one of these items, the other will drop. Despite the rumours, the order in which you kill the two Stevens has no impact on the item dropped.
The Caves
Fistula
It resembles Envy in how it behaves, beginning as a single entity before splitting into four smaller entities upon taking damage, which then each split into two with further damage. However, unlike Envy, when reduced to the lowest size, the sections become Chargers.
The smaller a piece becomes, the faster it moves around. Pieces can also collide with each other, which changes their direction. Because of this, it is recommended to leave bigger parts intact for as long as possible, and focus on one part at a time. That way, the movement of the parts is more predictable, making the parts easier to dodge. It is also advised to kill the Charger before moving onto the next part, if possible.
Despite floating in the air, Fistula and its parts cannot move over Rocks. However, as of the Wrath of the Lamb expansion, it can move over Pits. Note that a Charger/Boom Fly will not spawn if the smallest part is killed above a Pit.
Fistula appears regularly as a Mini-Boss starting from The Caves to Sheol. In The Caves and The Depths, it starts as two smaller entities, and in The Womb and Sheol, a whole Fistula appears.
Champion Variants
Dark Blue
In this form, it will initially split into three entities instead of four and will spawn Boom Flies and Red Boom Flies on death. This version of Fistula has slightly more health, is larger, and moves slower.
Gurdy
Behavior
Gurdy’s basic attack is firing five shots at once, in one of three different directions. This is indicated by her pulling her head inside, and making it reappear at another side.
Gurdy can also summon Attack Flies out of the pores on her body periodically to attack. On occasion, she will also spawn a Pooter/Fat Fly out of the larger pore on the right side of her body.
Lastly, she can summon two Boils (which can be replaced by a Gut or a Sack) at once in front of her, which is signaled by raising her arms.
Strategies
Since Gurdy does not move, she is balanced out by having a large amount of health to take down. This means that any Items that improve your projectile damage output will shorten this fight significantly. This also gives you a good time to use Bombs if you have any to spare, since you are guaranteed to hit and take a good chunk of health off of Gurdy.
It is preferable to take out any of the other monsters that Gurdy summons during the fight before focusing on her, so that they do not cause problems later on.
Sometimes, rocks will partially block your side paths, so that dodging Gurdy’s shots becomes more difficult. It may be worth it to clear them with bombs at the start of the battle (and hurting Gurdy in the process).
Standing behind her will prevent her from firing her 5-way shot spread at Isaac, and most of the Boil shots will not reach him. However, Flies are still dangerous in this position.
Another good strategy is to kill all of the enemies first, and go to a side you choose. That will cause Gurdy to shoot at you, but will take some time. Go to the other side to dodge her attack. Keep repeating, and Gurdy will be killed. This strategy will not work on the champion version.
If Gurdy spawns a Gut on one side of the room, the Gut’s explosive shots can hurt Gurdy and whatever else she spawns.
Champion Varieties
Black-Green
Peep
Before Peep does an attack, he will give a signal as to what attack he’s going to do.
A spray attack that sends ten urine projectiles flying out in a radial burst pattern. This is signalled by Peep smiling and bringing his hands to his face.
A jump that brings him crashing down on the location he last saw the player standing in. This is signalled by Peep smiling and throwing his arms wide.
Oozing out glowing puddles of yellow creep that deal 1 heart damage if you stand in them. These go away after 5–6 seconds, and don’t affect characters with flight. This is signalled by Peep frowning and slightly shrinking, along with him making a burping sound.
Additionally, at 66% and 33% health, he’ll detach one of his eyeballs and set it to bouncing around the room in diagonal lines. The eyeballs cannot be damaged at all until you kill Peep himself, so don’t waste your time shooting. They leave behind a purely cosmetic blood trail but do 1/2 heart of damage on touch normally and 1 if you are fighting him in The Womb. If you happen to run into Peep himself, beware that he always does a full heart of damage on touch.
Strategies
The following strategies have proven to work against Peep:
The biggest problem in dealing with Peep is the radial burst. You can dodge behind rubble piles (or hover above them if you have flight) to avoid the spray if there are any, but often you’ll be facing him in an empty room. Your best option there is to stay well away on his left or right side, moving back and forth between opposite sides of the room whenever he launches. At maximum range, you should be able to dodge the burst with just a little movement up or down to put you between shots. Don’t forget to watch for the eyeballs, they can sneak up on you if you’re too focused on Peep.
Because this fight requires so much dodging, items that require careful aim are best avoided. With good timing, bombs/Mr. Boom can be used to catch Peep when he lands after his jump. Spoon Bender or I The Magician can help greatly in keeping your shots more or less on target while you dodge the pee spray. Range increasing items will give you more room to maneuver; conversely, range reducing pickups like Number One or My Reflection will make your life harder in this fight. Continuous, sustained fire from maximum range is the order of the day here. His eyes are also slowed down by Skatole, making them easier to dodge.
The Spider’s Bite’s slowing tears effect affect Peep in an unusual way. While slowed, Peep’s jump will send him straight up into the air, then right back to where he launched from (as opposed to Peep launching and then landing at the location he last saw the player). This makes his pattern very predictable, as Peep can be kept at one spot indefinitely, with the player only occasionally needing to move to dodge the pee spray and eyeballs.
Despite being able to jump to great heights, he can’t move over rocks while airborne. This allows you to take cover behind or over rocks, but it can also mean that predicting where he lands can be tricky without following the urine trail he leaves while he’s airborne.
Notes
If II The High Priestess reduces Peep’s health below 33% health before his first eye comes loose, only one will be spawned. Graphically, he will have both eyes missing, but you will only have to dodge one for the remainder of the encounter.
Champion Variants
Green/Blue
Both of his eyes are out right from the beginning of the fight. Otherwise, he behaves the same as the original version.
Yellow/Orange
Is physically smaller and behaves like the original, but constantly leaves a urine-trail, even while in mid-air during a jump, which hurts the player if stepped on.
The Caves part 2
Chub
Behavior
Chub charges at Isaac quickly when he gets in her line of sight. However, Isaac usually has enough time to sidestep away. Dropping a Bomb in the path of her charge will cause her to eat it. This stuns her for a short time, and then explodes inside her, dealing a large amount of damage.
Chub can also spawn Chargers, up to a maximum of two at once. These Chargers can be destroyed by her own charge if they get in her way.
Notes
Chub is similar to Larry Jr. in that she has multiple segments that can be hit (these cannot be destroyed separately, however). Items that can pierce through enemies (Cupid’s Arrow, Technology/Technology 2, Shoop Da Whoop!, and so on) are a huge asset against her.
Unlike most attacks early in the game, Chub’s charge will deal a full heart of damage if it hits instead of half a heart.
Champion Varieties
Blue
When blue, she is much larger in size, much more resistant to knockback, and slow. Instead of spawning chargers, she’ll spawn blue Boils (Functions identically to regular Boils, and does not drop any Pick Ups upon death)
Orange
She is slightly smaller than normal, and she has much faster and more unpredictable movement, both when moving normally and charging at Isaac. She will spawn Spities instead of Chargers, up to a maximum of 2.
Mini-Chub
Outside of Boss rooms, Chub may occasionally spawn without her 3rd segment making her unable to spawn enemies. In this form, Chub may use the spawning animation, but will not spawn any enemies in this situation, leaving her briefly vulnerable. Typically spawns with two Larry Jr. bosses with her. This is an intentional weakening of the boss, possibly for balance reasons.
C.H.A.D
Behavior
While at first acting like its normal counterpart, C.H.A.D. shrinks in size and increases in speed as you damage it. It spits out Suckers throughout the fight.
When defeated, the Little C.H.A.D item will unlock if you didn’t have it. If Little C.H.A.D has been acquired before the C.H.A.D encounter either through the shop or the D6 C.H.A.D will drop an item from the normal boss loot table.
C.H.A.D is unlocked by clearing The Caves 20 times.
Notes
Like Chub, placing a bomb while C.H.A.D. is charging towards Isaac will cause him to swallow the bomb, stopping him for a second and then causing an explosion, which deals severe damage.
The Depths
Monstro II
Behavior
Besides having increased HP, Monstro 2 differs by the following:
His vomit has been upgraded to a Brimstone/Shoop Da Whoop!-style laser that he shoots left or right (look for him to grin before he fires).
His launch in the air attack has new effects. The first time he lands, he will spawn very large 8 direction shots. These deal a full heart of damage. The second time he launches and lands, he spawns four Suckers which explode into projectiles in the four cardinal directions. These 2 effects alternate in order, and he always launches twice in a row.
Having the Halo Of Flies or similar orbiting items will greatly increase survivability in this fight. Otherwise, just keep on the run to avoid the increased projectile fire.
Unlike Monstro, standing near to Monstro II will make it more likely that he will use his laser or hop towards you. This can make the fight significantly easier to manage, as he is much easier to hit when he isn’t continually jumping or spawning flies.
Since Monstro II always does the huge jumps twice in a row, you can use this to your advantage – on every second launch, drop a bomb before moving. When Monstro II lands and spawns Suckers, the bomb will explode, destroying most of the Suckers and dealing significant damage to the boss himself.
Strategies
An easy way to defeat him is to stand in front of him until he grins, then quickly run behind him before he triggers his blood vomit beam, then attack until he grins again. If done correctly, Monstro II will be defeated without giving him a chance to do his annoying leaps. A somewhat less risky strategy would be to get out of the way when Monstro II vomits, then quickly get back in the way when the attack ends and take a few quick shots at him until he grins again.
It’s also possible to get him stuck against the geometry of the bottom of the room and stand in such a way that his blood beam will not hit you, but still be close enough to cause him to only use this attack. If you can stand there and attack him, he will be continuously pushed against the geometry behind and below him, holding him in this sweet spot. Great for characters with low damage or speed and need to just sit there and whack at him for a while.
Champion Variants
Red
Monstro II becomes twice as fast and spawns only 2 Suckers on his second jump
Loki
Behavior
His main attack has three steps. He makes poses whilst attacking. First, he shoots 4 projectiles in a plus shaped pattern, followed by 4 shots in an X shaped pattern, and finishing with another 4 shots in a plus shapped pattern. His other attack shoots 8 projectiles in a circle around him.
He also randomly teleports himself during the fight.
He is sometimes assisted by a single Poky. At times, he may summon Boom Flies to accompany him, which can damage him upon exploding.
Notes
It is rare to find him as a boss. He is, however, very common in Sheol (encountered in pairs) and sometimes can be encountered in The Womb. He can be encountered in triplicate in The Chest.
Gish
Behavior
Gish’s attack pattern is similar to that of Monstro II. However, instead of a blood beam, he attacks with exploding projectiles that leave behind puddles of tar that slow down Isaac. Instead of Monstro II’s Sucker-spawning attack, Gish spawns two smaller Clots based on himself. Unlike with Monstro II, his first stomping attack does not produce any projectiles.
Gish is unlocked by clearing The Depths 30 times. Upon defeat, he will drop Little Gish if you do not already have it.
Strategy
Gish is an easy boss once you get the hang of his attack patterns. His leaps into the air are easy to avoid and his spawned Clotties are simple enemies. His tar ball attack is easy to dodge, as the player can just run in a circle and Gish will usually miss. With this fight, patience is the key.
The Womb
Scolex
Behavior
Scolex’s main method of attack is to pop out of the ground and jump at Isaac in an arc, and then burrowing back into the ground. He is completely immune to damage, except at the end of his red, blinking tail.
Scolex will also sometimes poke a part of his body out of the ground, exposing either his head or his tail. If it’s his head, he will fire 3 IPECAC shots at Isaac and dive back into the ground. If it’s his tail, he will fire multiple blood shots with varying sizes, similar to Monstro’s attacks.
Scolex is hard to hit, but has the lowest health of all bosses in the game. However, if the player has Wrath of the Lamb installed, Scolex’s health will be significantly buffed.
When Scolex pops out of the ground, if you hit his tail, you deal much more damage than when he exposes his tail and fire the blood shots.
Blastocyst
Behavior
In its largest form, Blastocyst can do a low hop, sometimes scattering bullets all over the place. It can also do a large jump shooting in 8 directions upon landing. It will split into two smaller versions upon taking enough damage.
In its next form, Blastocyst can shoot a 4 way shot either in the four cardinal directions or diagonally when it lands after jumping. It also splits into 2 smaller forms upon taking enough damage.
In its next form, it fires a 4 way shot in the four cardinal directions after being still for a short time. It does not shoot when landing after jump. It loses its bubble upon taking enough damage and becomes an Embryo.
Embryo
Triachnid
He hovers in the middle of the room much like Mom’s Heart and It Lives. He has four different attacks:
Stomping all three of his feet around the room.
Retracting into the air and stomping one foot at a time.
Spawning a Trite by coughing them up.
Slamming his own head into the ground to stomp Isaac, firing blood tears in 8 directions.
Its attacks are identical to Daddy Long Legs, except more white slowing creep comes from his ‘feet’ and using his headslam attack spews 8 diagonal shots across the room.
Unlike the other alternate unlocks (Steven, C.H.A.D. and Gish), Triachnid does not have a specific item drop.
Mom’s Heart
Behavior
Mom’s heart spawns two to four Monsters and then disappears. After killing those monsters, the heart will reappear in the middle of the room for 3–4 seconds, spawn more monsters, then disappear again. If you manage to kill the monsters within two seconds from their spawning (before the Heart disappears), Mom’s Heart will stay on screen and spawn a next pack.
Strategy
Provided you have bombs, placing a bomb just as the heart is about to drop into vision will not only damage the heart, but may also destroy any monsters the heart spawns; this can afford you essentially double the attack time against the heart.
When Mom’s Heart drops down to 33% health, it will stop hiding but continuously spawn monsters and start firing blood bombs similar to IPECAC shots. The explosions leave a large puddle of red Creep that damages Isaac on contact. The monsters it spawns in this phase are usually weaker, consisting largely of various small flies.
If you are lucky enough to make it to Mom’s Heart with technology, stand on the same horizontal line as it on either side and just hold down the attack button. If you’ve positioned yourself right, everything it spawns will be in the same line as your fire, effectively killing it and damaging the heart without any movement.
Alternatively, using The Bible will act as an instant kill, similar to using it on Mom.
It Lives
Behavior
Much like the Heart, It Lives spawns numerous enemies, however many of these are bosses.
The enemies spawned by It Lives are, at random:
Monstro
A Larry Jr. pair
The Duke of Flies
Chub
4 Leeches*
2 Eyes*
2 Freds
4 Suckers*
4 Knights*
Bosses spawned by It Lives will be spawned in order the first time, with Monstro being first, followed by Larry Jr., the Duke of Flies and finally Chub.
*Any normal enemy may randomly be replaced by one of its counterparts, including Kamikaze leeches, Holy leeches, bloodshot eyes, spits and Selfless Knight variants respectively.
Like in the Mom’s Heart fight, getting It Lives to approximately one-third health will cause it to constantly fire red IPECAC-like bombs that leave Red Creep behind. It will spawn different enemies, starting with 4 Suckers. The easiest way to counter this is to simply hug a wall and fire tears at it, as the bombs will rarely hit Isaac directly.
Strategy for defeating It Lives is generally the same as defeating Mom’s Heart, though it is advised to focus on dealing damage to It Lives whenever possible as avoiding a single boss such as Chub while fighting It Lives tends to be simpler than keeping up with the constant inflow of enemies and bosses.
Killing it for the first time unlocks the character ???, and the floor Sheol, otherwise accessed from the Devil Room. Accessing the Sheol devil room requires meeting the same criteria that spawns regular devil rooms. Killing it for the second time unlocks the immediate choice of Cathedral or Sheol upon completion, instead of the chest. Thus, you do not need a devil room spawn to get to Sheol on playthroughs 12+. If the Devil Room spawns after killing It Lives for the first time, you get the regular choice of Sheol (in the Room itself) or the Cathedral (when you come back from the Devil Room, the beam of light to the Cathedral will replace the final Chest when you leave the Devil Room), whilst further playthroughs will give you the choices side-by-side.
Notes
Just as with Mom and Mom’s Heart, It Lives can be instantly killed by using The Bible item.
Defeating this boss in future runs will no longer produce the golden chest for completing this game, instead requiring you to travel to Sheol or Cathedral to win instead.
If you have enough speed, running through the beam of light that will take you to the Cathedral and going into a Devil or Angel Room (if one spawns) will not take you to the Cathedral; instead, if you leave the Devil/Angel Room, the beam of light will be gone and you will be forced to go to Sheol.
Mom
Mom
Behavior
She has 4 basic parts:
Mom’s Foot: Mom’s main attack, used when Isaac is not near any of the four doors. Deals damage in a radius approximately equivalent to the shadow that it casts before contacting. This attack can damage other enemies in the room and even Mom herself, if the foot lands on Flesh or an Eye.
Mom’s Hand: An alternate attack used when Isaac is too close to a door between stomps. Mom will stop stomping for a short period if this attack is used. However, this attack happens very quickly and is much harder to dodge than the foot.
Mom’s Eye: Periodically appears in one of the four doorways. The eye does not attack or spawn enemies, offering a short period of time in which to damage Mom. (Note: Mom’s red champion version (see below) will fire a triple blood shot from the eye)
Mom’s Flesh: A lump of flesh that will appear and summon an enemy next to it. Mom can have up to 4 additional enemies assisting her during the fight.
Enemies summoned by Mom may include:
Gaper
Horf
Maw
Clotty
Mulligan
Charger
Spity
Globin
Strategy
Mom, like other bosses, has a single health bar that depletes when any of her body parts are damaged. All enemies and body parts will be destroyed when her health is brought to zero. A common and effective strategy is to stay in the center area of the room. This will prevent Mom’s hand from attacking and causing damage before it can be dodged. Use Mom’s friendly fire stomp damage to help keep the spawned enemies at bay during the fight; you might have to deal with range attacking enemies which won’t follow you to the center of the room. The corners of the room also do not cause the hand to attack, but may contain rocks that obstruct Isaac’s path and might allow pursuing enemies to catch up. Use bombs or Mom’s foot to clear a path of evasion against the enemies and foot damage.
Using XIX The Sun, XIII Death, Spider Butt, Blood Rights or Necronomicon are good choices against Mom because the effect will hit every body part active on the screen, which can cause very heavy damage.
As with all bosses, having Mom’s Bra is just as effective against Mom as it is against any other boss. Use the time that she’s frozen to deal as much damage to the leg as possible.
You can also stand near her eyes/other parts when she’s about to stomp. If you get away at the last second, she’ll stomp on her self, dealing massive damage to her.
Mom will not use her stomp attack if Isaac is standing very close to any of the 4 doors. (This seems to be implemented so that players cannot force mom to stomp herself without at least risking to take damage). So you just can stand there, shoot at the door and dodge spawned enemies until you kill her, scoring yourself a very easy victory.
The Bible
Book Of Revelations
Notes
Unlike lesser bosses, killing Mom ends the battle immediately, destroying all remaining enemies. (A Gaper can survive in the form of a Pacer or a Gusher. A Globin is also able to survive as a puddle that will regenerate shortly after. The Chest /Trapdoor will still appear after the Monster’s death.)
After defeating Mom, teleporting is the only way to exit the room, as the doors are destroyed when Mom is killed. Make sure to check every room and pick up every item on the floor before beginning the encounter (A door to the Devil Room may appear after a teleportation.)
In ReBirth, it’s possible for one of the walls to have a hole blown in it, as well as a door to the Devil or even Angel Room. The hole in the wall leads to the Throwback Boss Rush Room.
Since Wrath of the Lamb, if Isaac is standing in the shadow animation of Mom’s stomping attack when she is killed, the player will still receive 1 Heart of damage. It is unavoidable.
As of version 1.4, Mom will always drop The Polaroid (provided you’ve unlocked it).
According to the creator, this was a bug.
If you use the II High Priestess card on Mom she will not take damage.
In The Binding of Isaac: Rebirth, she seems to have a new voice actor. This makes her sound less like a monster and more like a genuine person.
In The Binding of Isaac: Rebirth, there is a chance for Mom’s severed hands to appear in The Depths II
Sometimes throughout the game (when you are not in the Mom battle) , Mom’s foot would randomly come down once.
Champion Variants
Blue
Mom spawns only enemies added in Wrath of the Lamb (Trites, Keepers, Big Spiders and B. Lickers) instead of the enemies she would normally spawn. (Added in Wrath of the Lamb 1.4)
Red
Mom stomps faster, uses her hands more often and shoots triple blood bullets from her eyes. This version does not spawn enemies at all.
The Harbingers
Famine
Behavior
Phase 1
Famine will begin his fight with a very fast charge to the left or right that will make him go through the walls and come back from the other side, stopping at his original location. After that, he will stay in practically the same spot and spawn a Pooter or a Fat Fly, capable of having a maximum of two at any given time.
For as long as these flies are on-screen, he will not move around much and will not charge until Isaac gets in his line of sight. These charges will destroy any flies in the way, so it can be an effective strategy to force him to charge as much as possible.
Phase 2
When he only has a third of his health left, his body and horse will be destroyed leaving only the head, and he will start saying “hey” as pestilence does in his first phase. He won’t be able to move around much or spawn any more flies, but it will fire fast-moving triple shots (one in the center and two in a split pattern to the sides) directly at Isaac’s location.
Notes
The charge deals a full heart of damage, instead of the usual half-heart damage found in the Basement/Cellar.
Champion Variants
Blue
Phase one attacks in a six-way pattern (no bullets in vertical directions). He also charges faster, at a much higher rate than normal. While charging, he moves slightly (diagonally if needed) towards Isaac, and makes a complete charge around the room rather than just stopping short as per his non-champion form. When he loses his body and horse, he’ll attack by vomiting bullets similar to Scolex or Monstro.
Eternal Variant
Phase one’s charge attack does not go through the walls, instead stopping at the end of the room. During its charge it shoots a ring of projectiles. His attack shoots a volley of projectiles in random directions, and spawns four Pooters and/or Fat Flys around him. Phase two’s attack shoots an additional 2 projectiles in a split pattern after the initial 3 projectiles.
Pestilence
Phase 1
Like Sloth, he fires a lobbed projectile similar to IPECAC, which explodes on contact, and does one heart of damage only. As Well, Pestilence says “hey”. It also leaves a pool of green creep upon exploding.
His movement leaves a large, green creep.
He summons Chargers and Spitties periodically.
Phase 2
After reducing his health to one half, his head is destroyed, leaving his body still mounted on his horse. It still leaves the green puddles of creep wherever it goes and fires the green bombs more rapidly. Also, the horse begins to summon red and black Flies, with the same coughing sound as the Hive (to compensate for the fact that he is no longer able to summon Chargers and Spitties during this phase).
Champion Variants
White
Phase 2 summons a small Spider and shoots 6 blood bullets.
War
Phase 1
While riding on his horse, he charges to the left or right and comes out on the other side, but does not stop until he has done 3 passthroughs. While charging, he will always enter the screen about 1/2 of the room height below where he left. If this distance would put him below the edge of the room, then he will come back in at the top of the room instead.
Also, while mounted, he shoots out an 8 directional shot, generally right after charging.
And also while riding, he will jump off and summon 5 Troll Bombs (similar to “The Tower” tarot card and “Anarchist Cookbook” item), wait for them to explode, and then land.
Phase 2
Activated when he reaches 50% of his total Health. Here, he will have lost his horse and will follow the player with extremely fast speed, similar to Lust or Gemini. However, like Gemini, he will occasionally pause to catch his breath, making a “splits” pose like the one Loki uses when firing bullets. He does this after you deal enough damage to him. Edmund also mentioned that he will slow down if you continue to attack him. It makes the fight easier for playthroughs with no speed upgrades.
If the player has the ability to fly, rocks will not protect him from War’s phase 2, as he will climb those rocks in order to attack the player.
Champion Version
Black
During phase 1, he leaves a Troll Bomb behind his path whenever he charges through the screen, and he will more frequently charge than regular War. He jumps off less often, but when he does, he summons 2 Mega Troll Bombs instead of half a dozen normal Troll Bombs.
During Phase 2, he normally chases you around the room, but when he is stunned, he fires out 6 bullets in six different directions. The champion War is also slower if the player continues to attack him.
He sometimes disappears from the screen completely after a jump attack. If you aren’t able to exit your current room or kill him through AoE (e.g. Necronomicon), your game will be lost. In this case, homing tears will go towards you (confirmed only in a Famine-War combinate room in The Chest).
Death
Phase 1
At first, Death rides on his horse, attacking by either summoning a quartet of scythes that travel across the room or summoning a pair of scythes that chase the player. With careful aim and enough firepower, the scythes can be shot down, which may be easier than dodging.
During the fight, Death is also capable of using the item The Hourglass against the player, reducing movement speed and slowing down tears for a few seconds.
Phase 2
When the boss reaches 50% health, he dismounts from his horse, which constantly sweeps horizontally across the room in an identical pattern to War’s charging attack.
The horse has a relatively high amount of hitpoints and damaging it will not reduce Death’s health bar, but must still be destroyed along with any summoned minions to finish the battle.
The unmounted Death will summon pairs of Knights to attack the player, with a small chance of spawning them as Selfless Knights. They will be killed if his horse happens to run into them. The horse may get hit upwards or downwards if it hits a knight at a certain angle.
Champion Varieties
Black
Is slightly larger and has more health than normal Death. He always spawns 4 scythes and instead of using the Hourglass, he spawns two Kamikaze Leeches. While separated from his horse, he periodically spawns two Red Maws instead of Knights.
The Seven Deadly Sins
Envy
Behavior
Envy moves around the room, damaging Isaac when he touches him. When his health reaches zero, he splits into two smaller, faster moving versions of himself that have less health. These smaller versions can split into two again, and those again, making it possible to have up to 8 mini-envies on the screen at once.
Strategy
It is recommended that the player focus specifically on one half split off from each division. This minimizes the total number of enemies that need to be kept track of, and makes the boss significantly more manageable. The general strategy is to split him in half, and then hit one half until he divides again. Repeat the process until the smallest divisions are destroyed. Then return to killing the slightly larger halves until the boss is defeated. This strategy is especially important when fighting multiple Envies in higher levels such as The Womb or Sheol. Alternately, if the room containing Envy has a natural barrier or alcove to stand in, you may use your natural knockback effect to remain virtually untouched. Attack flies, such as Forever Alone, are very effective against Envy, since if he touches the attack fly, he constantly and quickly takes damage as long as the fly is touching him.
The last mini-Envy killed will drop a Troll Bomb where it dies. Rarely, he may drop the Shoop Da Whoop! item.
Notes
It is possible for a part of Envy to become Blue and look like Super Envy. If a Blue head is killed last, it has a chance to drop the Forever Alone item instead of a Troll Bomb or a Shoop Da Whoop.
Isaac’s Last Will shows the cause of death as Pride when killed by Envy.
Pride
Behavior
In combat, he has two easy-to-spot attacks.
The first attack, forewarned by him making a “Troll” face, spawns 4 Troll Bombs in random sections of the room. He is immune to damage from his own troll bombs. The second attack, before which he makes a “Forever Alone” face, projects 4 wave-like lasers from himself in an X-pattern.
Pride may drop a Troll Bomb, Tarot Card, or the Anarchist Cookbook on death.
Strategies
The best tactic is to stay to his left or right, since the X-attack won’t hit you, and you can easily go up or down to avoid the bombs. Pay attention to the order the bombs spawn, because the first ones to explode will throw the others around the room. He is also immune to his own bombs, so you cannot use them to damage him like you can with Wrath.
Gluttony
Behavior
Gluttony has two attacks; an 8-way blood shot and a blood beam attack, similar to that used by Vis.
The room he appears in will always have the same setup, with Pits around him.
Strategies
Gluttony is a relatively easy mini-boss, with only two attacks. His blood beam attack is very easy to predict and takes a long time to charge, so it can be avoided quite easily. Likewise, the “pop” attack, where he fires shots, can be avoided with ease so long as Isaac keeps moving. Additionally, Gluttony will signal this attack by shivering for a short time before firing, making it easily avoidable. In general, do not spend too long directly horizontally or vertically of Gluttony, and only dash in to deal damage. Remember that as with Vis or Bloodshot Eye, the blood beam will go right through Rocks and other obstacles. Also keep in mind that while he does normal damage with his ranged attacks, he deals a full heart of contact damage. If you follow those steps, your main weakness is patience.
Gluttony drops several Hearts and half-hearts on death, and may drop the <3 item, which restores all HP and adds 1 Heart Container.
Notes
If Gluttony is frozen while using his blood beam, the attack will stay on screen and continue to hurt Isaac until it is unfrozen.
The blood beam is able to damage other monsters. This can be utilized in The Chest to quickly dispatch multiple Sins at once.
Sloth
Behavior
Sloth’s main attack is firing IPECAC shots. Sloth can also spawn Chargers. However, he can only spawn 3 Chargers on the screen at once. If one is killed, he may spawn another, but the number of Chargers that can be alive at once is 3.
He is similar to Pestilence in that he spawns Chargers and shoots green bombs.
Strategies
Sloth is one of the harder minibosses, with his ability to punish minor errors quite seriously. His IPECAC shots do one whole heart of damage without The Wafer. The most important strategy to use while fighting Sloth is to keep moving in a specific direction. Doubling back and forth can avoid the Chargers, but can often lead to the player getting hit by his IPECAC shots. The best strategy is to use his IPECAC shots’ explosiveness to the player’s advantage. The explosion caused by the shots destroy Rocks and kills the Chargers that he spawns. Use these to clear the room, and establish a circular movement pattern that doesn’t double back. This should cause all of his shots to miss, and present predictable moments of vulnerability, where the player can attack.
Sloth either drops a Tarot Card or, less commonly, Bob’s Rotten Head upon death.
Greed
Behavior
Greed attacks by firing fast-moving sets of 3 blood shots from his mouth and by summoning 2 Hoppers (which can be replaced by Trites if the player has Wrath of the Lamb installed) which also begin to attack Isaac. His shots cause Isaac to lose 3 coins, two will be dropped on the ground and one will be lost permanently. This also applies to any contact damage dealt by him.
Strategies
Greed is one of the harder sins to fight, as his triple shots are fast and he has no animation or sound to warn you before he attacks. His ability to spawn Hoppers is not a great threat, but they act as shields and can make it harder to dodge his projectiles. A general strategy is to stay far away if the player has enough range, and fire tears at him from afar. This allows the player ample time to dodge his basic attacks and deal with any Hoppers he spawns before they become a threat.
Bear in mind that Greed can fire and immediately turn to face Isaac if he moves far enough. He will still have the firing expression on his face for a second, but will not fire.
When defeated, Greed explodes in a variably big shower of coins, which can include nickels or dimes.
He may also drop the Steam Sale item, thus taking 50% off prices in shops when picked up.
When fighting Greed, try not to pick up the coins if you are hit. Because the coins are on the ground, it is impossible for you to lose them. If you pick them up and are hit, then you will lose even more coins.
Spawn Mechanics
Greed has a chance of appearing in any shop from the Caves/Catacombs 2 onwards. He will spawn in the Caves/Catacombs 2 shop with a 50% chance and always spawn in the shop after that, unless he spawned in the previous floor, spawned in the Secret Room (which happens from the Depths 1 onwards with a 33% chance) or a different Sin is going to appear in that level.
If you have obtained only The Compass but not the Treasure Map, you are able to spot Greed if he is in the Secret Room, since then there’s a miniboss icon that won’t reveal a grey room icon in the background even when you get next to it. Once you obtain the Treasure Map (or approach the room with Spelunker Hat or X-Ray Vision), the miniboss icon will disappear and you will see the icon for the Secret Room as usual, yet it will still contain Greed.
The Seven Deadly Sins part 2
Wrath
Behavior
Wrath attacks the player by shooting bombs, similar to the way Isaac fires bombs with Dr. Fetus. These bombs can damage Wrath, and can be pushed back by Isaac’s tears or by simply running into them.
Strategies
Wrath tends to have a very independent movement pattern, similar to Larry Jr. where he appears to move in a pattern that is not dependent upon where the player is.
His only attack of throwing bombs can be very damaging, but is easy to avoid. The simple strategy is to be attentive. As Wrath rarely will move aggressively towards the player, most of the attention should be paid to the arrangement of the room. However, when Wrath does touch the player, he deals 1 heart of damage.
As long as the player does not back into a corner and always has a line of escape, Wrath proves to be an easy adversary. Be cautious about the eventual troll bombs he can drop when he dies. If you fire tears at the bombs, they will move in the direction they are pushed and can deal damage to him if he is in the blast radius of them.
However, once in The Womb or Sheol, fighting multiple Wraths can be significantly more challenging. It is advisable that the player uses their own bombs to clear out the room, so that there are always multiple avenues of escape if cornered.
Wrath drops a few bomb pickups on death, and may drop Mr. Boom as well.
Notes
If the player has the Bobby-Bomb item, Wrath’s own bombs will home in on himself.
If the player is carrying a Remote Detonator, Wrath’s bombs will not blow up when he throws them and he will stand still until they do. This allows the player to wait until he throws a bomb and then blast him with tears. He will not respond, move, or fight back.
Wrath is immune to poison from Bob’s Curse, Bob’s Rotten Head and IPECAC.
Wrath’s bombs deal very small damage to himself and Super Wrath, but more damage to other enemies. Other explosions deal nearly Mega Bomb damage
Lust
Behavior
She’s quite fast and attacks by trying to deal contact damage, but has no other attacks.
Strategies
As stated above, Lust has no attacks other than simply chasing Isaac, which can be much more threatening than it seems. If Isaac has no speed boosts, or has even lost speed, Lust can be a very difficult boss. The best way to fight Lust seems to be to break sightlines as much as possible. Lust slows down to a “searching” mode when she loses sight of Isaac, and this can be used to add distance between the player and Lust. Using the spawned rocks and quickly turning corners can conserve hearts and make this fight easier. Use of bombs can block her movement, as she is unable to push them away, but also won’t walk around them.
Tears that induce slowness (including Ball of Tar and Little Gish) or fear (including Mom’s Perfume and Mom’s Bra) prove effective in negating Lust’s only method of dealing damage. Another way to defeat her with flight and/or spectral tears; this allows for a unique strategy in which a player flies directly over rocks and fires at Lust as she pursues. Due to Lust having no way to destroy the rocks, she’ll have no way to attack the player.
Lust drops The Virus or a random Pill upon death.