The Adversary (ザ・アドバーセーリ Za Adobāsēri) is the posthumous version of the Dark One and encountered on the first floor of Necropolis and can appear with another Adversary in regular rooms in the Dark Room and the Chest.


The Adversary takes the exact appearance of the Dark One with a broken left horn (similar to that of Azazel). His body was wrapped with multiple white bandages resembling to a mummy. He also has the ability to stretch a cut from his stomach which was hidden by couple of wrappings.


The Adversary has multiple attacks:

  • Like The Dark One, The Adversary is capable of darkening the entire room by standing still and roaring. He performs this attack randomly.
  • Every time the player lines with The Adversary either horizontally or vertically, he can fire a homing Brimstone laser. This attack has no reaction time or clear indication, just like the Bloat.
  • The Adversary may open his stomach, spawning 3 spiders.
  • The Adversary may fly off the top of the screen.After several seconds, he flies down,headbutting the earth creating a circle of earthquake shock-wave (very similar to Mega Satan`s fist smash).


The Adversary is arguably one of the most frustrating boss in earlier floors, since all of his attacks are hard to avoid. However, there is still some strategies to make the fight easier.

His Brimstone lasers are very threatening because they can target on the player, dealing at least one time damage. Notice that they are not completely homing; the beam curves more when it goes further, exactly like the tears of the boss Isaac. This makes standing close to the Adversary a good strategy because he lacks short-range attack.

The earthquake shock-wave attack is easy to dodge if the player has enough speed, however otherwise it is almost unavoidable. Pyromaniac will negate the damage of earthquake shock-wave since it is considered as an explosion.

When the Adversary releases spiders, it is suggested to kill the spiders at first (especially when you can one-hit them), otherwise they may block Isaac's way when he's trying to flee from the Adversary`s Brimstone.

During its darkening attack, the Adversary is extremely vulnerable, so its a good timing to hit him.


  • "Adversary" is another word for "enemy" or "foe".
    • It is also another name for Satan.
  • From his "V.S" sprite, The Adversary's mouth is visible. From in-game, however, his mouth was covered with wrappings.
The Binding of Isaac / Rebirth
Regular bosses Original: BlastocystChubDuke of FliesThe FallenFistulaGeminiGurdyLarry Jr.LokiMonstroPeepScolex
(Wrath of the Lamb: Daddy Long LegsGurdy Jr.Mask of InfamyPinWidow)

Rebirth: Dark OneDingleGurglingsThe HauntMama GurdyMega FattyMega MawMr. FredPolycephalus
(Afterbirth: BrownieDangleLittle HornRag ManTurdlings)
(Afterbirth †: Big HornRag Mega)

Posthumous Bosses Original: Monstro II
(Wrath of the Lamb: The Blighted OvumThe BloatCarrion QueenThe HollowThe HuskLokiiTeratomaThe Wretched)

Rebirth: The AdversaryThe CageThe Gate
(Afterbirth: The ForsakenThe FrailThe Stain)

Alternative Bosses Original: C.H.A.D.GishSteven
(Wrath of the Lamb: Triachnid)

Rebirth: Sisters Vis (Afterbirth †)

Harbingers Original: WarFamineDeathPestilenceHeadless Horseman

(Wrath of the Lamb: Conquest)

Final Bosses Original: It LivesMomMom's HeartSatan
(Wrath of the Lamb: ???Isaac)

Rebirth: The LambMega Satan
(Afterbirth: HushUltra Greed)
(Afterbirth †: Delirium)

Seven Deadly Sins EnvyGluttonyGreedLustPrideSlothWrath
Seven Super Deadly Sins Super EnvySuper GluttonySuper GreedSuper LustSuper PrideSuper SlothSuper WrathUltra Pride
Angels / Demons Original: Krampus

Rebirth: GabrielUrielFallen Angels

The Legend of Bum-bo
Regular bosses BygoneDuskGibsGizzardaLoafPeeperPyreSangreShy GalThe Duke
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