The tome would turn anyone who read it into a devout worshiper of Cyric and thus would increase Cyric's power. The tome was of great power and once one started reading it, could not willingly stop; it even worked against other deities. The final version of the Cyrinishad was the 398th version, and all the previous authors had suffered greatly for their failure to satisfy Cyric.
The book was made of raven-black leather, and was embossed with a pattern of small grinning skulls and sunbursts against a twisting, warped background of torture and chaos. The book had golden hinges and clasps, and it was closed with a lock of unbreakable metal.
A skull the size of a child's fist dominated the front cover. The skull was animated by Rinda's blood and acted as the guardian of the book, which prevented it from being destroyed or removed from the mortal realms.
After Mask managed to trick Cyric into leaving the book in his hands, it was given to Rinda the Scribe for safekeeping, where it was protected and concealed by Oghma. Later, Gwydion the Quick joined Rinda as guardian of the book. They kept it hidden from Cyric and his followers for a long time, until Malik el Sami yn Nasser (who would later become the Seraph of Lies) managed to track them down at Candlekeep.
Malik was unsuccessful in his quest to obtain the holy Cyrinishad. The follower of Cyric heard the holy tome hissing aggressively in his mind, and he detected an extremely bad scent. He immediately recognised that his enemies meant to throw the Cyrinishad down to the vile, lower levels of Candlekeep, where it could not be retrieved.