The Book of the Dead is an unseen artifact that is housed inside The Library.
Powers[]
Although it was seen on the series, its exact contents are unknown. It probably contains information about the evil gods and demons of Egypt, as Flynn thought that its contents would help defeat Apep.
Real Life Counterpart[]
The Book of the Dead was the name given to a series of old Egyptian texts detailing how a dead person could reach the afterlife, without being harmed by the many dangers that lurked in the Underworld.