Your counter attacks cause opponents to take a penalty against you.
Prerequisites: Str 15, Improved Unarmed Strike, Combat Reflexes, Behemoth Style, BAB +5.
BENEFIT
While in the Behemoth Style, once per round, whenever an opponent successfully damages you with a melee attack, you can make an attack of opportunity against that enemy. If your retaliatory unarmed strike deals damage to an opponent, that opponent takes a -2 penalty on attack and damage rolls against you until the beginning of your next turn.