Binding of Isaac: Rebirth Wiki
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A Strange Door locked

A Strange Door is a special exit that is unlocked by beating Boss Mother secondphase ingameMother for the first time. It leads to a special version of MausoleumMausoleum/GehennaGehenna II, which contains Collectible Dad's Note iconDad's Note, which starts the Ascent, and eventually HomeHome and the fight against Boss Dogma ingameDogma and Boss The Beast ingameThe Beast.

The door spawns in the starting room of DepthsDepths/NecropolisNecropolis/Dank DepthsDank Depths II. It can be opened by giving it Collectible The Polaroid iconThe Polaroid or Collectible The Negative iconThe Negative. This can be done through methods such as using a teleportation card, a Telepills, a teleport activated item, Collectible Ventricle Razor iconVentricle Razor, or Collectible Forget Me Now iconForget Me Now after defeating Boss Mom ingameMom, escaping the boss room. The door can also be opened with Broken PadlockBroken Padlock, Collectible Cracked Orb iconCracked Orb, Faded PolaroidFaded Polaroid, Soul of CainSoul of Cain, or Collectible Sharp Key iconSharp Key, but not Collectible Mr. ME! iconMr. ME!, Collectible Dad's Key iconDad's Key,Mysterious PaperMysterious Paper, or a Get out of Jail Free CardGet out of Jail Free Card.

Having more than one of Collectible The Polaroid iconThe Polaroid or Collectible The Negative iconThe Negative, (such as through Collectible Diplopia iconDiplopia or Collectible R Key iconR Key) will only remove one to open the door. Faded PolaroidFaded Polaroid is always taken first if held, then The Negative and then The Polaroid.

A Marked Skull always spawns somewhere in the second floor of the chapter. Destroying it will drop a guaranteed 0 - The Fool0 - The Fool (or a Telepills if holding Collectible Little Baggy iconLittle Baggy), giving a reliable way to open the door. It is recommended to visit the Boss RushBoss Rush room for a free item before teleporting out if possible. Please note that if the player has Collectible Little Baggy iconLittle Baggy and Collectible False PHD iconFalse PHD, the Telepills will become a ???, rendering it more difficult to exit the boss room.

Note that defeating Boss Hush ingameHush three times counts towards unlocking A Secret Exit A Secret Exit, allowing the player to unlock CorpseCorpse without unlocking the Polaroid or Negative. This makes the Faded PolaroidFaded Polaroid, Collectible Sharp Key iconSharp Key, or Broken PadlockBroken Padlock the only ways to open the door until these items are unlocked.