It is a religious act performed by priests of the cult of the Demon Lord referred to commoly as bAdvibe. The act is intended to bring the priests into closer attunement with the Demon, to get closer to his thoughts and desires.
This is a dangerous practice and has been known to drive many priests to irrevocable insanity. Intense meditations, fasting and preparation is required before performing the ritual. A curious side effect of the ritual are visions, the source of which are hotly debated in theological circles. Frequently the visions are clearly of events not of our world and consequently are usually dismissed as fanciful or delusional. In any event, none recorded have yet been useful.
This particular tome (known generally as the Archive of the DoomRiTuaL) is the personal abridged selection of the Chief Archivist who finds the visions a fascinating diversion. The Archive of the Doomritual is held on public display in the Grand Library of the capital city Dul Araya most days.