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Mom's Heart is a boss that can appear on the second floor of Chapter 4 (Error: The given stage ("The Womb") does not exist., UteroUtero), and is the final boss of Endings 1-11.

After being killed 11 times, Mom's Heart is permanently replaced by It Lives. However, even after being replaced by It Lives, there are a few circumstances in which Mom's Heart can still be fought:

Behavior

Phase 1

At the beginning of the fight, Mom's Heart is always accompanied by 2 Eyes. After awhile, Mom's Heart retreats upwards, becoming invulnerable and launching four diagonal lines of red projectiles in a spread that slowly rotates clockwise. When each original Eye is killed, another one spawns in its place.

After the second set of Eyes have been killed, Mom's Heart alternates between two attacks:

  • Lowers itself and shoots red projectiles in different patterns:
    • 10 projectiles in all directions that expand outwards either continuously or in a pulsating manner.
    • 3 pulsating curved lines of projectiles that rotate and expand outwards.
    • 2 rings of ten projectiles that pulsate outwards at different intervals.
    • A single line of projectiles that follows Isaac.
    • 8 slightly curved lines of projectiles that rotate and expand outwards.
    • 5 lines of projectiles that mimic Isaac's movements (these lines have no space between projectiles).
    • 4 curved lines of projectiles that continuously rotate and expand outwards.
  • After performing one of these projectile patterns for long enough, Mom's Heart retreats upwards again, shooting the same four slow-moving lines of projectiles, and spawns 2 enemies of a singular type:
  • After all enemies have been defeated, Mom's Heart lowers itself and repeats the entire process.

Phase 2

  • After reaching 60% HP, Mom's Heart beats faster and no longer retreats upwards and instead performs projectile attacks and spawns enemies simultaneously.

Phase 3

  • After reaching 10% HP, Mom's Heart stops its previous attacks and shoots four diagonal Collectible Brimstone iconBrimstone lasers that rotate either clockwise or counter-clockwise for a duration before stopping for a moment and then repeating the attack.
    • At the very top of the boss room is a small area where the heart's hitbox is active and can deal contact damage.
  • Upon defeat, Mom's Heart fires out a ring of 14 projectiles.

All of Mom's Heart's projectile attacks can hurt and kill spawned monsters.

(in Repentance) Behavior in Mausoleum/Gehenna

Phase 1

The beginning of this fight is similar to one from Chapter 4, as Mom's Heart is always accompanied by two Eyes and retreats upwards after awhile, shooting the same four slow-moving lines of projectiles. However, a second pair of Eyes does not replace the first, and after both initial Eyes are killed, Mom's Heart lowers itself and no longer retreats upwards.

  • Mom's Heart then shoots red projectiles in completely unique patterns:
    • 2 interwined rings of 8 projectiles that expand outwards at different speeds.
    • 2 lines of projectiles that rotate and expand outwards in a spiral motion.
    • 5 lines of projectiles that rotate and pulsate outwards.
    • A ring of 12 projectiles that expands outwards, along with 2 rings of 4 projectiles that expand outwards and rotate in opposite directions at a higher speed.
    • 2 rings of 8 projectiles that expand outwards and rotate in opossite directions, creating curved lines that encase certain areas.
  • Unlike in Chapter 4, it does not spawn monsters of any kind. Due to this, its behavior does not change despite beating faster after reaching 60% HP.

Phase 2

  • After reaching 10% HP, Mom's Heart stops its previous projectile attacks and fires 2 Brimstone lasers in opposite directions that slowly rotate either clockwise or counter-clockwise at a steady pace. During this, it also shoots 2 continuous streams of projectiles, one that follows Isaac's movements and the other mirroring the first.
  • Upon defeat, Mom's Heart fires out a ring of 14 projectiles, identical to its Chapter 4 encounter.

Gallery

Unlockable Achievements

  • A Noose
    A Noose - Defeat Boss Mom's Heart ingameMom's Heart 3 times.
  • Everything Is Terrible!!!
    Everything Is Terrible!!! - Defeat Mom's Heart 5 times.
  • Ipecac
    Ipecac - Defeat Mom's Heart 6 times.
  • ???
    ??? - Defeat Mom's Heart 10 times.

Everything Is Terrible!!! changes

After beating Mom's Heart 5 times, the following playthroughs have the following changes:

  • Bosses drop 1 less health pickup.
  • The chance of a floor receiving a curse increases.
  • (in Repentance)Unlocks Half Soul Hearts

Notes

  • Every time Mom's Heart is defeated changes the current savefile's image until It Lives is unlocked.
  • Until It Lives is unlocked, Mom's Heart cannot be continued past unless a Devil Room or an Angel Room appears, which allows access to SheolSheol or the CathedralCathedral, respectively.
  • Just like Mom, Using Collectible The Bible iconThe Bible against Mom's Heart will kill it instantly.

Trivia

  • Mom's Heart appeared in the original The Binding of Isaac.
    • In the original Binding Of Isaac, the only attack Mom's Heart could perform was spawn 2-4 monsters before disappearing and repeating the same move each time the wave of monsters were killed off.
  • The music that plays during this fight is titled Ventricide. Ventricide is a made-up word formed from the word ventricle (one of the two larger chambers of the heart) and the suffix -cide, which denotes an act of killing. This theme is used in other tracks, such as Matricide, Hericide, and Infanticide.
  • If Isaac gets hit by Mom's Heart's Brimstone attack, Mom's laugh can be heard.
  • (in Afterbirth † and Repentance) As of Booster Pack #5, since the Scarred Womb can only be unlocked after defeating It Lives 30 times, Mom's Heart can no longer appear in that environment.
  • (except in Repentance) During the versus screen, Mom's Heart's enemy-spawning sound can be heard. Mom's Heart is one of seven bosses that can be heard during the versus screen, the other five being (except in Rebirth) The Stain, (except in Rebirth) The Forsaken, (in Afterbirth † and Repentance) Big Horn, Mom, (except in Repentance) It Lives and (in Repentance) Mother.
  • (in Repentance) Despite having a Womb layout, Mom's Heart's room in the Mausoleum/Gehenna does not have the red fog effect of the Womb.

Bugs

Bug Bug! (in Rebirth and Afterbirth) Sometimes, if the boss intro is skipped, the game will not teleport Isaac into the center of the bottom of the room, resulting in immediate contact damage with one of the Eyes or Mom's Heart, depending on the direction of the room's entrance.


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