With a single touch you can reduce the threat of even the most savage of foes.
Benefit: You must declare that you are using this feat before you make your attack roll (thus a failed attack roll ruins the attempt). On a successful hit, the attack deals no damage and bestows no other effect or condition, but the target cannot cast spells or attack (including attacks of opportunity and attacks as immediate actions) for 1 round unless it succeeds on a Will saving throw with a DC of 10 + 1/2 your character level + your Wisdom modifier. You may attempt a touch of serenity once per day for every four levels you have attained (but see Special), and no more than once per round.
Special: A monk of the lotus receives Touch of Serenity as a bonus feat at 1st level, even if he does not meet the Prerequisites. A monk may attempt a touch of serenity a number of times per day equal to his monk level, plus one more time per day for every four levels he has in classes other than monk.
Advanced Player’s Guide. Copyright 2010, Paizo Publishing, LLC; Author: Jason Bulmahn.