Shivering Fist

Your unarmed strike chills your target to the bone.

Prerequisite(s): Con 13, Wis 13, Improved Unarmed Strike, base attack bonus +8.

Benefit(s): You must declare you are using this feat before you make your attack roll (thus, a failed attack roll ruins the attempt). Shivering Fist forces a foe damaged by your unarmed attack to succeed at a Fortitude saving throw (DC 10 + 1/2 your character level + your Wis modifier), in addition to dealing damage normally. A defender who fails this saving throw uncontrollably shivers for 1 round. A shivering creature can take no actions, becomes vulnerable to cold, and loses his Dex bonus to AC, if any. Creatures immune to cold are immune to the shivering effect but still take damage normally. You may attempt a shivering attack 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 katabonic chill receives Shivering Fist as a bonus feat at 1st level, even if he does not meet the prerequisites. A monk may attempt a Shivering Fist attack 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.