Aberrate

The caster transforms one creature into an aberration.

Book of Vile Darkness 3.5
By Monte Cook

Transmutation [Evil]

Level: Sorcerer/Wizard 1
Components: V, S, Fiend
Casting Time: 1 action
Range: Touch
Target: One living creature
Duration: 10 minutes/level
Saving Throw: Fortitude negates
Spell Resistance: Yes

The subject’s form twists and mutates into a hideous mockery of itself. The subject’s type changes to aberration, and it gains a +1 natural armor bonus to AC (due to the toughening and twisting of the flesh) for every four levels the caster has, up to a maximum of +5.