Binding of Isaac: Rebirth Wiki

Added in Repentance

The Beast is a boss added in The Binding of Isaac: Repentance DLC. She appears in Home Home and is the final boss of Ending 22 and The Binding of Isaac as a whole.


After defeating Dogma Dogma, Isaac is given Dogma Dogma, granting him flight and allowing him to traverse The Beast's 2D Crawl Space-like arena. Dogma Dogma also grants a one-time Holy Mantle Holy Mantle shield, the effect of The Wafer The Wafer (if playing in Normal Mode), Prevents Isaac's speed from going under 1.1, and +2 damage, and heals him up to 6 hearts with Red Heart Red Heart Containers and Soul Heart Soul Hearts.

At the start of the fight, The Beast sits inactive in the background. Flying around The Beast are four Ultra Harbingers, which attack Isaac one at a time in the order of Ultra Famine Ultra Famine, Ultra Pestilence Ultra Pestilence, Ultra War Ultra War, and Ultra Death Ultra Death. Once they have all been defeated, The Beast lets out a roar, submerges into the lava, then reemerges on the right side of the screen, beginning her fight.

Phase 1[]

During her first phase, The Beast uses the same sequence of attacks indefinitely:

  • Charges towards Isaac, forcing the screen to scroll while harmful, destructible stalagmites and stalactites move towards Isaac.
    • The screen scrolls along with The Beast, meaning that she will not actually get closer to Isaac even if he doesn't move; this attack only brings the stalagmites and stalactites on-screen.
  • At the end of the charge, The Beast begins to inhale large rings of fire which have one small gap that Isaac can fit through.
    • Any remaining stalagmites or stalactites on screen are destroyed at the start of this attack.
  • After inhaling 8 rings of fire, The Beast stops and fires a colossal Brimstone Brimstone-like beam that covers the bottom and middle portions of the screen.
  • After this attack, she performs a quick charge across the screen before repeating the initial charge again in the opposite direction. Similar to the Brimstone Brimstone-like beam directly before, it covers a large portion of the bottom and middle parts of the screen.

Even if The Beast's HP drops below the threshold for her second phase, this will always still be the first attack she performs every single time.

Phase 2[]

The Beast enters her second phase below 6660 HP and loses her inhaling attack, but gains 2 new ones. Additionally, during the charging attack, there are more rocky obstacles and some stalactites are cracked and fall when Isaac passes underneath. (As before, the screen scrolls while The Beast charges, with Isaac's position on the screen being maintained.)

At the end of a charge, The Beast performs one of two attacks:

  • Opens her mouth and fires 3 radial waves of slow-moving fire, then firing 6 radial strings of fast-moving projectiles which travel through the gaps left between each fire.
  • Roars and spawns 4 Beast Souls which chase Isaac and charge at him, trying to predict his movements, before dissipating.
    • Any remaining stalagmites or stalactites on screen are destroyed at the start of this attack.

After using either of these attacks, The Beast submerges into the lava and causes glowing orange lines to appear beneath Isaac and in other random areas. The glow of these lines increases in intensity over time before launching out a large fiery projectile that flies up and falls back into the lava. The Beast gradually increases the rate at which projectiles are launched before eventually reemerging from the lava on the opposite end of the screen and launching a small burst of large fiery projectiles arcing in all directions.

  • Any remaining stalagmites or stalactites on screen are destroyed at the start of this attack.

Phase 3[]

The Beast enters her third phase at approximately 33% HP and is indicated by a burst of blood. The Beast is forced to submerge into the lava and reappear on the other side of the screen, then begins charging towards Isaac indefinitely while more stalagmites and stalactites spawn behind him. (As before, the screen scrolls while The Beast charges, with Isaac's position on the screen being maintained.) Cracked stalactites do not appear during this phase.

Once The Beast's HP reaches approximately 2000, her horns crack and her body ruptures in boils. She degrades through two more stages: losing 2 horns and an eye upon reaching roughly 1000 HP, and losing another eye, another horn, all of her teeth, and generally having a melted look upon reaching roughly 500 HP. Upon defeat, a large light ray comes from above and strikes her down, followed immediately by Ending 22.



The roar The Beast makes in the background before emerging in the foreground.

The growl The Beast makes before the four ghosts are summoned to attack Isaac.

The sound of ghosts rising after being summoned.

The sound of lava balls being shot from underneath the ground.

The sound of a choir playing while The Beast is smote by a beam of holy light. It serves as a prelude to ending 22.

Unlockable Achievements[]

Damage Scaling[]

Damage scaling is an unclear mechanic introduced by Nicalis in The Binding of Isaac: Afterbirth to provide a more challenging experience to the players, enabling some enemies to retaliate against high-damage attacks by deploying an "armor" of a sort to greatly reduce the amount of damage taken. Further details and an in-depth explanation may be found here.


  • Phase 2's narrow activation period (from 50% to 33% health) means it will often be skipped, typically if enough damage is done during the long-duration fire rings attack.
  • Censer Censer makes it nearly impossible to avoid damage when The Beast inhales lines of fire, because it changes the speed of just the fires within its area of effect. Instead of having a consistent gap in each line of fire, the gap may be filled in by other lines of fire moving at inconsistent speeds.
  • Chaos Card Chaos Card doesn't work on The Beast.
  • Era Walk Era Walk, "I'm Drowsy..." pill, etc. works for the duration of the fight, and makes for an easy battle.
  • Sprinkler Sprinkler will float in the air for the duration of the flight and remains in place during the chase sequence, providing constant extra damage.
  • Plan C Plan C works and will kill The Beast before dying, triggering Ending 22. It must be used after all four Ultra Harbingers are defeated, or else it will only kill the current Ultra Harbinger.
  • Teleport! Teleport! cannot be used to escape the fight; instead, Isaac will be teleported to a random spot on the screen. This holds true for other methods of teleportation, such as Cursed Eye Cursed Eye.
  • Ipecac Ipecac and Haemolacria Haemolacria travel in an arc, similar to Ultra Pestilence's shots, and are extremely hard to aim. If Isaac has high range when firing left or right, the projectiles will go up and off-screen.
  • Most non-flying familiars, such as Cube of Meat Cube of Meat, Leech Leech, or Blue Spiders, are almost completely useless against the Ultra Harbingers, as the familiars will stay stuck in the lava on the bottom of the arena. However, they are able to damage Ultra War if his movement pattern takes him close enough to the bottom of the screen, and The Beast as she is half-submerged in lava.
  • Any item that gives an effect for the room, such as Box of Friends Box of Friends or The Book of Belial The Book of Belial, will work for the entire fight, starting with Ultra Famine.
  • Broken Watch Broken Watch can affect this fight. However, it only activates for 1 unvisited room out of 4. Finishing the fight with Dogma and beginning the fight against the Ultra Harbingers counts as a new visited room. Hence, to have the effect against The Beast, the last visited room in Home must be the 3rd after the effect was triggered for the last time.
  • Gnawed Leaf Gnawed Leaf works as normal in this fight — as long as Isaac stays still and has some way of dealing damage without moving or firing, such as an enemy-chasing familiar. He will eventually kill The Beast with enough patience.
  • Homing Trisagion Trisagion will stay on-screen indefinitely during this fight.
  • Flat Stone Flat Stone makes tears travel straight down, as there is no ground they can skip on.
  • Like Flat Stone Flat Stone, bombs fired with Dr. Fetus Dr. Fetus will be fired in a downward arch since there's no ground for them to slide on, making it a difficult item to use in the fight without bomb immunity items such as Pyromaniac Pyromaniac or Host Hat Host Hat.
  • Defeating each Ultra Harbinger will grant Isaac's active item 2 charges, similar to the Boss Rush.
  • All items that grant extra lives will revive Isaac on the spot rather than returning him to the previous room.
    • Accordingly, Dead Cat Dead Cat is incredibly useful in the fight, due to the large amount of lives it provides Isaac.
  • The Soul The Soul is capable of dragging The Forgotten The Forgotten with him as he moves. This means he can move anywhere on the screen, but at a much slower rate. Tainted Forgotten Tainted Forgotten flies during this battle and stays where he ends up when thrown (in mid air), meaning that if you throw him at the Beast you can constantly attack her during the chase scenes.
  • The hitboxes of stalactites, stalagmites, and the lava persist during The Beast's death animation.
  • The stalactites and the stalagmites, while acting like obstacles, actually count as enemies, allowing abilities that proc on enemy death or damage, like the Sigil of Baphomet Sigil of Baphomet, to work with them. This trinket in particular makes the chase portions a breeze, as The Beast destroys the stalactites and stalagmites automatically.
  • Despite not being able to fly or go over gaps in its final form, Bumbo Bumbo will be able to "fly" around the arena and deal damage without sinking in the lava. Bombs placed by Bumbo still behave normally and fall down.
  • Tears that go up and off-screen, such as those created by Lachryphagy Lachryphagy explosions, are affected by "gravity" in this fight and fall back down at an enemy. It's unknown if this is a bug or a feature.
  • The Ludovico Technique The Ludovico Technique is very difficult to use. The unique tear seems to be teleported back to the player sometimes, maybe because it gets "lost". Because of the screen scrolling, it may be dragged out of the screen if the player doesn't make it move with the scrolling. Keeping the tear in sight, making it move, moving the character to avoid obstacles such as stalactites, and taking care of The Beast all at the same time is a mess, unless having a synergy that makes the tear more visible and/or very powerful. With powerful synergies, The Ludovico Technique The Ludovico Technique can make this fight very easy. However, without it, it makes it harder.
  • Bombs are affected by gravity and are hard to hit the Ultra Harbingers with, but can easily be used against The Beast, especially during chase sequences. As such, it is a great strategy to continuously use all of your bombs during this sequence, as there is no longer any other need for them.
  • Because there are no walls or floors for tears to collide with in this fight, the damage boost from Dead Eye Dead Eye will not fade away.
  • Items that place Poops, such as The Poop The Poop or Hallowed Ground Hallowed Ground, cannot place poops during the fight.
  • The lava projectiles from both the lava and when The Beast rises afterwards can be slowed and knocked down with certain slowing items such as Censer Censer and high knockback tears.
  • Night Light Night Light is not recommended for this boss battle, as it can cause flames to pile up unavoidably during the Beast's fire ring inhalation attack.


  • The Beast is heavily based on the first Beast described in the Book of Revelation.
    • The Beast's theme is called "Revelations 13-1", referencing the section in the Book of Revelation describing the first Beast.
      • A narration performed by Matthias Bossi reads the second verse of this passage during the cutscene prior to The Beast's fight. This narration says, "And the beast which I saw was like unto a leopard, and his feet were as the feet of a bear, and his mouth as the mouth of a lion: and the dragon gave him his power, and his seat, and great authority."
  • The Beast is the only boss to be preceded by an introductory cutscene rather than a VS screen.
    • The cutscene depicts Isaac being crushed by a giant static cross that rises from the remains of Dogma, which turns his tears into static. Following this, the room begins collapsing, revealing a hellish cavern while Isaac sprouts a pair of wings and flickers between resembling ??? ???, The Forgotten The Forgotten, and The Lost The Lost. Isaac then flies up to face The Beast rising up from the lava.
      • Isaac's flickering between ???, the Forgotten, and the Lost is a reference to the events of Ending 20.
  • The Beast is one of the only 2 bosses to take place in a Crawlspace-like side-scrolling environment, the other being Rotgut Rotgut.
  • At the end of the fight, Isaac's father refers to The Beast as "the Mother of Harlots".
  • The Beast appears to be wearing a tattered version of Mom Mom's dress, suggesting that she is yet another interpretation of Mom from Isaac's perspective.
  • When using the "I'm Drowsy..." pill during the battle with the Ultra Harbingers, there is one extra slow sign in the position of where The Beast will be, indicating that The Beast is actually "hidden" below the lava before the Ultra Harbingers are defeated.
  • Revelations 13-1 is the longest track in the entire Rebirth OST, sitting at 7 minutes and 53 seconds. This makes sense, as the theme is highly dynamic, changing depending on where the player is in the fight.
    • During the section that plays while fighting The Beast, Latin chanting can be heard in the background sometimes. The chanting is "mori bestia, cum nostra lucis", which is a mistranslation of "die, Beast, to our light". A more accurate translation would be "Morere, besti, ab luce nostra".
  • In Revelation, it is said that the Lord is the one who defeats The Beast, which may explain the beam of light that comes down to kill The Beast.
    • If The Beast is affected with any Status effects as she dies, the beam of light changes color. This is likely because the beam of light is part of The Beast's frames and not a different entity entirely.
  • Enemies turned into poop with E. Coli E. Coli or other means affect the game's scrolling, as the poop will remain on the screen regardless of whether or not the screen is scrolling.
  • In the fight's background, each of the four Harbingers can be seen doing a small animation before they fly into the foreground. Ultra Famine chuckles, Ultra Pestilence raises his fists in the air, Ultra War becomes enraged, and Ultra Death facepalms before brandishing his scythe.
    • They can also be seen doing a small animation whenever Isaac takes a hit. Ultra Pestilence waves his arms and grins, Ultra War raises his arms and then "slams" them down, and Ultra Death laughs. Ultra Famine doesn't have one because he is the first Ultra Harbinger to come into battle.
  • According to the game files, The Beast's boss fight takes place in Hell itself.
    • Despite being in a standard fire-and-brimstone depiction of Hell, Isaac's last will still retains Home's "some cold place" location line, suggesting some level of illusion to the events of The Beast.
    • Edmund McMillen has referred to the place as the Lake of Fire on Twitter.[1]
  • The Beast is confirmed to be female.[2]
  • The four Beast Souls that The Beast spawns may be a reference to The Binding of Isaac: Four Souls, a card game created by Edmund McMillen.
  • The Beast was teased initially in a post made to Steam by Edmund 5 days before Repentance's release, which included an artwork that featured her faint silhouette in the background.
  • The skull of The Beast can be seen in the icon for the Dead God Dead God achievement.
  • The earlier concept art depicts The Beast to have extra four heads based on the Harbingers.[3]
  • Edmund McMillen noted that the Beast sequence, along with the Tainted Characters and Dogma, were initially reserved for a possible Isaac sequel.[4]


Bug Bug! If the player has Knockout Drops Knockout Drops, a sufficiently high amount of luck, and an item that fires multiple tears at once (such as Monstro's Lung Monstro's Lung), they will be capable of knocking the Ultra Harbingers far off the screen during The Beast's fight. This also occurs if the player has Strange Attractor Strange Attractor and enough sources of tears being fired. Ocular Rift Ocular Rift and Lodestone Lodestone can provide similar effects.
Bug Bug! D7 D7 or D100 D100 will respawn all the Harbringers and The Beast. If The Beast was charging during that time, the camera will continue to scroll infinitely, potentially causing a softlock due to the Harbringers going out of bounds.
Bug Bug! Blood Rights Blood Rights can still damage The Beast even when she is in the background, and can erroneously initiate her third phase before all of the Ultra Harbingers are defeated. The Beast remains intangible during this phase, but can still deal contact damage to Isaac.
Bug Bug! If the player has Bone Spurs Bone Spurs, the floating bones will prevent Ultra Death from appearing. A possible fix is to shoot off screen to the left or towards the lava. This can also cause Ultra War to appear at the bottom of the screen during its phase.
Bug Bug! Much like Dogma, If the player were to spawn The Beast into a room other than her main area via Debug Console and deplete its HP, the defeat animation and chorus upon defeat will play as normal, but the game will crash shortly after, due to a sequence break.
Bug Bug! If via any means the player manages to spawn a Golden Troll Bomb in the Beast fight, it will start to rapidly explode inside of the Beast when she spawns. The rapid explosions will cause her to die in mere seconds upon spawning, causing for an easy kill.