The Book of Torak is the Angarak holy book. It was apparently written by Torak himself in first person narrative. Like the Book of Alorn, the Book of Torak narrates the major world events, but tells it from a different perspective. According to the book, it was Torak who led the Gods to create the world, protagonists (such as Belgarath) are recast as villains, and the reason for Riva Iron-Grip being able to touch the Orb of Aldur (Or "Cthrag Yaska" as it is called by Torak) is different. The book also claims that the Angaraks are in fact the good race, and that Torak is good as well.
The prologue to Enchanter's End Game was based on this particular book.