The Binding of Isaac Wiki

Isaac (boss)

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Xxx form2Isaac RebirthKeeper sprite

For information on the character, see Isaac.

Isaac is a new Boss added with the Wrath of the Lamb DLC. He is the game's main character as the final, fixed boss of The Cathedral.


Phase 1

Isaac will appear lying down in the center of the room, crying on the floor. He shoots 12 high-velocity tears in a radial burst and will retaliate with streams of tears when hit.

Phase 2

At 66% of his health, a light will shine on Isaac, and he jumps from the ground. Isaac will then start shooting 4 large purple tears, which home slightly, in all directions. He will still retaliate with some tears when hit.

Phase 3

Triggered near 33% of Isaac's health. Isaac will grow angel wings, smile, and start floating. White beams will be randomly shot down from the sky (Similar to Crack The Sky and White Pony), Angel Babies will start spawning frequently (up to a maximum of 6), and the same homing projectiles from before will be shot in six directions at the same time. At this point, Isaac will no longer retaliate with tears when hit.


  • Using The Bible during or after the fight will instantly kill the player (Similar to ??? and Satan) unless they have The Wafer item, which will deal 1/2 heart damage instead.
  • Using items with a high fire rate (Such as Technology 2) is dangerous in this fight, as Isaac will retaliate with a very large amount of tears upon being hit, unless you have mom's contacts. This also applies to effects which apply damage rapidly, such as Mom's Knife.
  • Applying slow effects such as Little Gish or Spider Bite to Isaac will not affect the speed of his homing tears, but will slow all normal tears.
  • Activating Mom's Bra or triggering the special effect of Mom's Contacts will prevent Isaac from spawning enemies or attacking at all—including when damaged—for the duration of the effect.
  • Isaac cannot be damaged by the Crack The Sky light beams, or by his own. However, any Angel Babies in the fight can take a small amount of damage from his light beams.
  • It is possible to reduce Isaac to 0 health. If Isaac is on 0 hp, the wings and light will disappear, and Isaac will resume crying on the floor. No projectiles/beams of light will be used (just like when ??? (boss) is reduced to 0 hp). However, any angels spawned from the previous phase will still survive, and will continue to attack you.



  • If the player uses The Hourglass, Isaac will fire blood tears instead of the usual blue tears and purple homing tears.
  • If the player is killed by the light beams in the final stage of the battle, the Last Will will display a picture of War.


  • The third form is referenced in the DLC's trailer, which showed Isaac sprouting wings.
  • When in Phase 1, Isaac makes the same weeping noises as the Mulligan.
  • When Isaac was first added in the initial release of Wrath of the Lamb, his third form only consisted of the rays of light, except with a tremendous rate of firing.
  • The picture of Isaac on Isaac's Last Will is identical to that of the Mulligan, but without the bloated head.


Destruyendo -It lives- y -Isaac- en The Binding of Isaac02:22

Destruyendo -It lives- y -Isaac- en The Binding of Isaac

Isaac boss fight in 101:15

Isaac boss fight in 1.4 Petden

Isaac fight in 1.4

The Binding Of Isaac Isaac00:49

The Binding Of Isaac Isaac

Isaac vs Isaac Petden03:10

Isaac vs Isaac Petden

Isaac fight + Ending + Getting Dad's Key

Binding of Isaac Isaac (boss) under 30 seconds00:43

Binding of Isaac Isaac (boss) under 30 seconds

Regular Bosses
Blastocyst button

Chub button

Daddy Long Legs button

Daddy Long Legs
Dark One button

Dark One
Dingle button

Duke of Flies button

The Duke of Flies
Fallen button

The Fallen
Fistula button

Gemini button

Gurdy button

Gurdy Jr button

Gurdy Jr.
Gurgling button

Haunt button

The Haunt
Larry Jr button

Larry Jr.
Little Horn
Loki button

Mama Gurdy button

Mama Gurdy
Mask of Infamy button

Mask of Infamy
Mega Fatty button

Mega Fatty
Mega Maw button

Mega Maw
Monstro button

Mr Fred button

Mr. Fred
Peep button

Pin button

Polycephalus button

Rag Man
Scolex button

Widow button

Posthumous Bosses
Adversary button

The Adversary
Blighted Ovum button

The Blighted Ovum
Bloat button

The Bloat
Cage button

The Cage
Carrion Queen button

Carrion Queen
The Forsaken
The Frail
Gate button

The Gate
Hollow button

The Hollow
Husk button

The Husk
Lokii button

Monstro II button

Monstro II
Teratoma button

The Stain
Wretched button

The Wretched
Alternative Bosses
CHAD button

Gish button

Sister Vis button

Sisters Vis
Steven button

Triachnid button

Conquest button

Death button

Famine button

Headless Horseman button

Headless Horseman
Pestilence button

War button

Final Bosses
XXX button

Isaac button

It Lives button

It Lives
Lamb button

The Lamb
Mega Satan button

Mega Satan
Mom button

Mom's Heart button

Mom's Heart
Satan button

Ultra Greed
Seven Deadly Sins
Envy button

Gluttony button

Greed button

Lust button

Pride button

Sloth button

Wrath button

Seven Super Deadly Sins
Envy button

Super Envy
Super Gluttony button

Super Gluttony
Super Greed button

Super Greed
Super Lust button

Super Lust
Super Pride button

Super Pride
Super Sloth button

Super Sloth
Super Wrath button

Super Wrath
Ultra Pride button

Ultra Pride
Angels / Demons
Krampus button

Angel button

Angel button

Angel button

Fallen Angels
LEGENDS: The Binding of Isaac bosses are yellow. Wrath of the Lamb bosses are teal. Rebirth bosses are orange. Afterbirth bosses are crimson. Afterbirth † bosses are violet.

Start a Discussion Discussions about Isaac (boss)

  • OMG!

    5 messages
    • wrote:Versed isn't a verb, "it's" suggests present tense while "was" is past tense, the second and third "it's" should be "its", ...
    • all i am seeing is a random run post, dont we have a page for that?
  • That's my (sad) history

    15 messages
    • dead cat is pretty inconvenient, as somebody who plays azazel the bob's brain item is a game-ender, though
    • Bobs brain Is maybe a game ender But it Is when you play the lost I call bobs brain a kamikaze Item Also on my list Are BBF and Fire mind

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