Binding of Isaac: Rebirth Wiki
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A Strange Door locked.png

A Strange Door is a special exit that is unlocked by beating Mother Mother for the first time. It leads to a special version of Mausoleum Mausoleum/Gehenna Gehenna II, which contains Dad's Note Dad's Note, which starts the Ascent, and eventually Home Home and the fight against Dogma Dogma and The Beast The Beast.

The door spawns in the starting room of Depths Depths/Necropolis Necropolis/Dank Depths Dank Depths II. It can be opened by giving it The Polaroid The Polaroid or The Negative The Negative. This can be done through methods such as using a teleportation card, a Telepills, a teleport activated item, or Forget Me Now Forget Me Now after defeating Mom Mom, escaping the boss room. The door can also be opened with Broken Padlock Broken Padlock, Cracked Orb Cracked Orb, Faded Polaroid Faded Polaroid, Soul of Cain Soul of Cain or Sharp Key Sharp Key, but not Dad's Key Dad's Key, Mysterious Paper Mysterious Paper, or a Get out of Jail Free Card Get out of Jail Free Card.

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

A Marked Skull always spawns somewhere on the chapter. Destroying it will drop a guaranteed 0 - The Fool 0 - The Fool (or a Telepills if holding Little Baggy Little Baggy), giving a reliable way to open the door. It is recommended to visit the Boss Rush Boss Rush room for a free item before teleporting out if possible.

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