Murderous Intent

Prerequisite(s): Base Attack Bonus 9+, Favored Enemy (any one).
Benefit: Choose one creature of a type or subtype you have selected as a favored enemy. As a full-round action, you can make a single melee attack against the chosen creature. If you deal at least 1 point of damage, that creature must make a Will save (DC 10 + 1/2 your character level + your Cha modifier). On a failure, it is overcome with dread and can take only a move action or a standard action on its next turn. You automatically confirm any critical threats made against a favored enemy.
Source: Elder Evils