3e SRD:Stunning Fist
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Stunning Fist [General]
Prerequisite: Dex 13+, Improved Unarmed Strike, Wis 13+, base attack bonus +8 or higher.
Benefit: Declare that the character is using the feat before making an attack roll (thus, a missed attack roll ruins the attempt). It forces a foe damaged by the character's unarmed attack to make a Fortitude saving throw (DC 10 + one-half the character's level + Wis modifier), in addition to dealing damage normally. If the defender fails his saving throw, he is stunned for 1 round (until just before the character's next action). A stunned character cant act and loses any Dexterity bonus to Armor Class. Attackers get a +2 bonus on attack rolls against a stunned opponent. The character may attempt a stunning attack once per day for every four levels attained, and no more than once per round.