Create Greater Undead

Necromancy [Evil]
Level: Cleric 8, Death 8, Sorcerer/Wizard 8

This spell functions like create undead, except that you can create more powerful and intelligent sorts of undead: shadows, wraiths, spectres, and devourers. The type or types of undead you can create is based on your caster level, as shown on the table below.

Caster Level	Undead Created
15th or lower	Shadow
16th-17th	Wraith
18th-19th	Spectre
20th or higher	Devourer

SRD