Undeath To Death

Necromancy
Level: Clr 6, Sor/Wiz 6
Components: V, S, M/DF
Area: Several undead creatures within a 40-ft.-radius burst
Saving Throw: Will negates

This spell functions like circle of death, except that it destroys undead creatures as noted above.
Material Component

The powder of a crushed diamond worth at least 500 gp.