Your unarmed strikes are particularly damaging to chaotic creatures.
Prerequisites: Wis 19, Improved Unarmed Strike, Stunning Fist, any lawful alignment.
Benefit: The character’s unarmed strike is treated as an axiomatic weapon (it is lawfully aligned and deals an extra 2d6 points of damage against creatures of chaotic alignment). This ability doesn’t stack with similar abilities.
Source: Standard Reference Document under Open Game License v1.0a, which updated this feat originally published in the Epic Level Handbook, page 66.