Key to Death
The Men of Letters, some time ago, procured a very important item. A black key. Handle in the shape of a skeleton. It can open a door to Death's library.
The Key to Death was acquired at some point by the Men of Letters. Also known as the Black Key, it was described by Sergei as having a handle in the shape of a skeleton and can open a door to Death's Library. However, the key itself resembles an ornate brass skeleton key with a small skull at the top of the handle.
The key will generate a doorway leading to Death's Library upon reading the following Latin inscription from the key's case:
Viator mortalis, cave quoniam scias Clavem Mortis pensare graviter. Il tamen desideres, ut introeas illum abyssum, obscurissimum artis opus est tibi porta.
The portal will appear as the glowing outline of a door, but it can only be opened completely when the key is inserted into the keyhole.
When Castiel calls on the shaman Sergei to help with Sam's wound, Sergei puts Sam's life in danger, then states that he will only heal Sam if Castiel and Eileen find the Black Key and give it to him. However, Castiel has arranged for Bobby to monitor Sergei's niece, Anna, and he threatens to have her harmed if Sergei does not heal Sam.
In order to speak with Billie, Sam and Castiel search through the lore about the key before looking through the bunker's artifacts. Castiel eventually locates the key inside of a box with a red skull on it. When Sam reads the Latin inscription on the box, the key glows and a doorway appears on the nearby wall, leaving behind a keyhole. When Sam turns the key, the door to Death's Library opens for him.
Once he's in the library, Sam discovers that Billie isn't there. Instead he finds the Cosmic Entity, who is waiting to talk to her. Sam manages to convince it to allow him to return with the book describing God's death. When Sam returns, he removes the key from the lock, shutting the door.
- The Key to Death is able to generate a doorway by itself, unlike the Key to Oz, which requires the key to be inserted into a real door's keyhole.