|Although this article is based on canonical information, the actual name of this subject is conjectural.|
The Demonic Disguise Spell was a form of glamour that enabled a caster to create the illusion of transforming into a demon. The spell allowed the target to be seen as a massive red demon with horns and wings. Although the demon appeared to be physically bulky, the spell did not affect the target's physical strength and endurance to any degree, making the target susceptible to any damage that would normally harm him or her without the disguise. The caster of the spell could target anybody, including himself or herself.
This spell was cast by Jonathan Levinson on himself to prevent Buffy from discovering the Trio's plans, and to allow the Warren and Andrew to escape. Before the spell was cast, Warren suggested to Jonathan to get his Magic Bone, suggesting the artifact may have been used to complete the disguise.