Soul Reap

Classes Mystic 4
  School necromancy
  Casting Time 1 standard action
  Range medium (100 ft. + 10 ft./level)
  Area 20-ft.-radius spread
  Duration instantaneous
  Saving Throw Will partial, see text; Spell Resistance yes
  You engulf an area in a comet-like spiral of energy, untethering the souls or animating vital essence from undead in the area. Each undead creature in the area takes 10d8 damage and is staggered for 1 round. A creature that succeeds at a Will saving throw takes half damage and ignores the staggered effect. Mindless undead receive no saving throw. This spell has no effect on creatures that are not undead.