Power Word Stun

Power Word Stun
(Player's Handbook v.3.5, p. 263)

Enchantment (Compulsion) [Mind-Affecting]
Components: V,
Casting Time: 1 standard action
Range: Close (25 ft. + 5 ft./2 levels)
Target: One creature with 150 hp or less
Duration: See text
Saving Throw: None
Spell Resistance: Yes

You utter a single word of power that instantly causes one creature of your choice to become stunned, whether the creature can hear the word or not. The duration of the spell depends on the target's current hit point total. Any creature that currently has 151 or more hit points is unaffected by power word stun.
Hit Points Duration
50 or less 4d4 rounds
51-100 2d4 rounds
101-150 1d4 rounds