The Shade Isle Campaign
The Domstag Codex is the unholy scripture of the Church of Acrefatum. It is bound in human flesh and inked in blood, as evil magical books tend to be. The first pages contain simple charms and incantations for warding off the power of Law and opening magically-held doors, but the rest of the book very quickly devolves into insane philosophy, vile theology, mind-warping Lovecraftian Yog-Sothothery, and the worst sort of flagrant cliché.
At present, the Codex is buried away in the vaults under Dämmendell, locked and chained inside an iron chest packed with consecrated rock-salt.