Mastery of the Dead( Player's Guide to Eberron, p. 125)
You have learned to calculate the precise location of Dolu r r h at any given time, and to use that knowledge to capture the souls of creatures slain with your death spells.
Whenever you slay a c r e a t u r e with a spell that has the death descriptor, you can attempt a caster level check (DC 10 + slain creature's HD) as a free action to transform the slain creature's spirit into a ghost under your control. (See the ghost template in the Monster Manual for details.) If the check succeeds, the ghost appears in the slain creature's space at the beginning of your next t u r n and acts immediately. It follows your spoken commands (even if you don't share a language), even attacking its former allies if you so choose. It remains present for a number of rounds equal to your caster level (or until you are slain, whichever comes first). While the ghost is present, the corpse can't be returned to life by any means. You can't have more than one ghost present simultaneously with this feat. If you create a second ghost while your first ghost is still present, you can choose which one remains (the other disappears, its soul freed from your control).