Power Word, Stun

When a power word, stun is uttered, any creature of the magic-user's choice will be stunned — reeling and unable to think coherently or act — for 2 to 8 (2d4) melee rounds. 

Of course, the magic-user must be facing the creature, and it must be within the spell caster's range of ½" per level of experience. 

Creatures with 1 to 30 hit points will be stunned for 4-16 (4d4) rounds, those with 31 to 60 hit points will be stunned for 2 to 8 (2d4) rounds, those with 61 to 90 hit points will be stunned for 1 to 4 (d4) rounds, and creatures with over 90 hit points will not be affected. 

Note that if a creature is weakened due to any cause so that its hit points are below the usual maximum, the current number of hit points possessed will be used