Decaying Grimoire is an item available in Dragon's Dogma.
- "An old book of untold magick. Infused with the power to summon spirits."
Generally obtained by combining book fragments obtained for defeated Skeleton Mages - it can also be stolen from them using Master Thief.
Also occasionally found in chests, including on Bitterblack Isle, and is sold by Akim in The Everfall (Post-Game)
On use, a randomly selected dark magic spell is cast, including shortlived spells akin to Vortex Sigil, or a spell like Necromancy.(verify)