Needs review
Source: Way of the Open Hand

Description: You seem to evade all attacks through expertise in Tenshido

Prerequisites: WIS 13, Improved Unarmed Strike, Base Attack Bonus +9, Tenshido Novice, Tenshido Intermediate, Tenshido Advanced, Tenshido Expert

Any time you successfully trip an opponent they must make a Fortitude save (DC10 + your Wisdom modifier + 1/2 your character level) or suffer two points of Dexterity damage. Unlike normal dexterity damage this damage heals at a rate of one point per hour.