Mom's Heart

Mom's Heart is a boss that can appear on the second floor of Chapter 4, 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:
 * Prior to Booster Pack #5, it could also appear in the.
 * It can still appear in the Nightmare Boss wave of Chapter 4 in Greed/Greedier Mode.
 * It has a chance to appear in one of the boss rooms in.
 * After the defeat of the stronger version of Mom on second floor of Chapter 3.5, a flesh door appears, which can be opened if Isaac has collected both and . Behind it, a stronger version of Mom's Heart can be fought.

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 at near the top of the arena.

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.
 * 2 streams of projectiles that spiral outwards.
 * 2 rings of ten projectiles that pulsate outwards at different intervals.
 * 8 slightly curved lines of projectiles that rotate and expand outwards slowly.


 * 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 a number enemies of a singular type:
 * 3 Flesh Mobile Hosts
 * 3 Globins
 * 2 Eyes
 * The type of monsters spawned each wave is determined always follows the above order.
 * In the same manner as the original Eyes, a copy of each individual monster spawns again following the defeat of the original one.


 * 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 slightly faster and continues the same behavior but includes new projectile patterns and replaces the types of monsters it spawns.
 * Its projectile patterns now include:
 * A single line of projectiles that follows Isaac.
 * 5 lines of projectiles that mimic Isaac's movements (these lines have no space between projectiles).
 * 3 pulsating curved lines of projectiles that rotate and expand outwards. This pattern can occasionally change direction of rotation.


 * Its spawned monsters are now:
 * 3 Lumps
 * 2 Swingers
 * 3 Globins

Phase 3
After reaching 30% HP Mom's Heart beats much faster and no longer retreats upwards and instead performs projectile attacks and spawns enemies simultaneously. However, after finishing each projectile pattern if there are any monsters alive, it will not perform another pattern until they are killed. In addition, a second wave of monsters no longer spawns after the first is killed.
 * It gains one new projectile pattern:
 * 4 curved lines of projectiles that continuously rotate and expand outwards.
 * It loses the projectile patterns from the first phase except for the following 2:
 * 2 streams of projectiles that spiral outwards.
 * 8 slightly curved lines of projectiles that rotate and expand outwards slowly.


 * Its spawned monsters are now:
 * 4 Walking Boils
 * 4 Tumors
 * 4 Hearts

Phase 4
After reaching 20% HP, Mom's Heart stops its previous attacks and shoots four diagonal lasers that rotate either clockwise or counter-clockwise for a duration before stopping for a moment and then repeating the attack.
 * The direction the lasers rotate depends on which is closest to Isaac when they are fired. The closer laser will rotate after Isaac and the rest will follow.
 * The duration the beams rotate can be: 1 rotation, 1 and a half rotations or 2 whole rotations.
 * 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.

As most of Mom's Heart's projectile attacks are synced with the rhythm of the heart's beating as the fight progresses the speed of each projectile attack increases.

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

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 begins with 3 projectile patterns she can perform:
 * 2 rings of 8 projectiles at different intervals that expand outwards overlapping on each other either continuously or in a pulsating manner.
 * 2 streams of projectiles that spiral outwards and gradually increase in density.
 * 2 rings of 8 projectiles each ring expanding and alternating between rotating clockwise and counter-clockwise.

Phase 2
After reaching 60% HP Mom's Heart beats slightly faster and replaces the patterns from its first phase with the following patterns:
 * 5 lines of projectiles that rotate and pulsate outwards.
 * A combined ring of 2 rings of 8 projectiles that rotate in opposite directions while expanding.
 * 16 wavy streams of projectiles that intertwine and create gaps.
 * 16 streams of projectiles that curve back towards Mom's Heart and intertwine to create gaps.
 * 5 waving lines of projectiles that rotate and expand outwards.

Phase 3
After reaching 30% HP Mom's Heart much faster, keeps the patterns from its previous phase and gains the following patterns: She also regains 2 patterns from her first phase:
 * 6 curved lines of projectiles that rotate in opposite directions while expanding- 3 clockwise, 3 counter-clockwise.
 * 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 streams of projectiles that spiral outwards and gradually increase in density.
 * 2 rings of 8 projectiles each ring expanding and alternating between rotating clockwise and counter-clockwise.

Phase 4
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 and permanently causes the Curse of Darkness and gray-scale effect for the entire floor. This persists for a brief moment upon entering.

A majority of Mom's Heart's projectile attacks use large projectiles and deal a whole heart of damage, however, some attacks can be mixed with, or fully use smaller projectiles which only deal half a heart of damage. The heart's lasers also only deal half a heart of damage.

As most of Mom's Heart's projectile attacks are synced with the rhythm of the heart's beating as the fight progresses the speed of each projectile attack increases.

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.
 * Unlocks Half Soul Hearts

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.
 * 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.
 * 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 The Stain,  The Forsaken,  Big Horn, Mom,  It Lives and  Mother.
 * Despite having a Womb layout, Mom's Heart's room in the Mausoleum/Gehenna does not have the red fog effect of the Womb.
 * If you die by the final wave of bullets after killing Mom's Heart, you will be rewarded the respective ending and it will count as a Mom's Heart kill, though it will not count for your win streak
 * Originally in Antibirth the Mausoleum version of Mom's Heart could spawn enemies like Bouncers and Blurbs.

Bugs
Mom's Heart