A 12 volume book in English, written by the members of the Cult of Gla'aki between 1800-1865. The book is fragmentary, with one cult member taking up where the last left off, and deals with the worship, powers and methods of summoning Gla'aki, Y'golonac, Daoloth and other Great Old Ones. The book was published in a pirated, edited 9 volume version, published in 1865 as a folio, which is more common. A rumour claims that originally there were only 11 volumes but a man on Mercy Hill (England) dreamed and wrote the 12th volume. Copies of the 9 vol. version are held by many major libraries and by private collectors. Hand-written 11 (a set of old type loose-leaf notebooks, the pages covered in archaic handwriting) and 12 volume versions are almost unheard of. There has been some talk of volumes 13 or 14, but such volumes are unknown. It is once called The Secret Revelations of Glakki.
The Revelations of Gla'aki was created by Ramsey Campbell; Chaosium have expanded the data.