Charnel Fire

With sinister flame and brimstone, the caster completely consumes one dead body so that absolutely nothing remains.

Book of Vile Darkness 3.5

By Monte Cook

Necromancy [Evil]
Level: Cleric 5
Components: V, S
Casting Time: 1 minute
Range: Touch
Effect: One corpse
Duration: Instantaneous
Saving Throw: None (Will negates for undead)
Spell Resistance: No (Yes for undead)

A creature whose body is destroyed by a charnel fire spell can only be brought back to life through a true resurrection spell. If this spell is cast upon a corporeal undead, the creature gets a Will saving throw, and the caster must overcome its Spell Resistance (if any). If the undead creature fails its save, it is destroyed forever.