The Book of Kreeth is a book written by the archhagsfiend, Kreeth. It contained her magics and experiments and was written in very ancient Krakish. The front cover had a picture of one of her creations, the Puffowl, the hideous crossover between a puffin and an owl. Most of the contents of the book contained frightening pictures and diagrams.
The book ended up in Trader Mags's possession. While she was setting up her shop in the Shadow Forest, Stryker, a Pure One soldier obtained it from her. Later, Coryn and the Band came for the same book. Trader Mags reluctantly gave out what she knew.
Nyra, the Pure Ones' leader was planning to use the book in order to start a process of transformation from the waters at the Tunnel of Despair and the ashes of Kludd's bones. During a battle at the cave, a Dire Wolf named Cody sacrificed his life in keeping the book away from the Pure Ones.
The Book of Kreeth was later taken back to the Great Tree. Otulissa studied the contents. It was fortunate that Nyra wouldn't have understand much of the book, but Otulissa can't either, as the words have been written is in very ancient Krakish. It was decided for now the book is to be kept secret and possibly have Bess try to translate some of the pages.
When the burning of the books by the Blue Brigade started, Fritha, Otulissa's student made sure that the book was safe from the enemies' talons.