An ancient and forbidden Bajoran book holding the rites to free the Pah-wraiths from the Fire Caves, studied by Kai Winn and Dukat in the final episodes.
The Book of the Kosst Amojan has been locked in the Bajoran archives for centuries, and only the Kai may consult it. In the closing arc of Deep Space Nine, Winn Adami, bitter at being passed over by the Prophets, turns to the Pah-wraiths and sends for it at the urging of Dukat, who is disguised as a Bajoran farmer.
Its pages appear to be blank. In The Changing Face of Evil, Winn's aide Solbor discovers who her companion really is and threatens to expose them both, and she stabs him. His blood falls on the book and the hidden writing appears.
Dukat later tries to read it and is struck blind. In What You Leave Behind, the pair carry the book to the Fire Caves and begin the ritual; Sisko ends it by hurling himself, Dukat and the book into the flames.