Hunters of Undeath (3.5e Epic Spell)

This spell summons 12 ghost eaters and provides all of them with damage reduction 8/magic and a +7 enhancement bonus to their Strength scores. The sheer number of these anti-undead machines is bound to make short work of most vampires, liches, wights, etc. The spell's casting time and requirement for a lot of extra spellcasters means that you'll probably need to cast it well in advance from a safe location, so the spell lasts for a whopping 10 minutes to make sure that the ghost eaters can reach, locate, and slay their target. Keep in mind that ghost eaters are rather weak monsters, even with the buffs provided as they're summoned, so your party may need to follow them to their target to provide backup...

XP Cost: 8,000 XP (for primary caster and the 12 extra spellcasters casting the highest-level spells (epic, 9th, 8th)) and 6,000 XP (for the 30 extra spellcasters casting the high-level spells (7th, 6th))