Time to build on some ideas!
Cost: 6 magic points; 2D6 Sanity points
Casting time: one hour
A zombie must have first created through a separate ritual and feed a freshly killed human within a day. Once the spell is complete and the zombie feed, the zombie will enter a torpor where it will begin to violently shake, distend, and tearing flesh as it elongates and transforms into a ghoul with the whole process closely related to a the process of becoming a werewolf. It will gain all statistics of a ghoul and retain more memories of its past life. Watching this transformation requires a sanity check (2/1d10) by anyone who did not cast the spell.
Alternative names: Ritual of the Awakening Mind, Undead Communion, Food of the Undead Gods