Quell the Profane

Power Attack (PH) , Resounding Blow (BE) , STR 13, base attack bonus +8,

Whenever you deal a critical hit to an evil creature using a melee weapon with which you are proficient, your opponent must succeed on a Fortitude save (DC 10 + 1/2 your character level + your Cha modifier) or take 1d4+1 points of temporary Strength damage. A monk's unarmed strike is considered a melee weapon for purposes of this feat.

Whenever you deal a critical hit to an evil creature using a melee weapon with which you are proficient, your opponent must succeed on a Fortitude save (DC 10 + 1/2 your character level + your Cha modifier) or take 1d4+1 points of temporary Strength damage. A monk’s unarmed strike is considered a melee weapon for purposes of this feat.

Your mightiest attacks weaken evil foes.