Freezing the Lifeblood

 
Prerequisite(s): Wis 17+, Base Attack Bonus 10+, Improvedunarmedstrike, Stunning Fist
 
Benefit: You must declare that you are using this feat before your attack roll. When attacking a humanoid creature, you can make an attack that deals no damage, but has a chance of paralyzing the target. On a successful hit, the target must make a Fortitutde check against DC = 10 + 1/2 Char level + Wis modifier. If the target fails the save, it is paralyzed for 1d4+1 rounds. Creatures immune to stunning are not affected by this attack.
 
Source: Complete Warrior