Needs review
Source: Rokugan Campaign Setting

Description: You have learned the ultimate distraction technique

Prerequisites: Improved Disarm, Combat Expertise, INT 13, Base Attack Bonus +10, Bluff (Class skill), Strike at the Tail

Required for: Blackened Sight

If you successfully feint in combat and attack your opponent while he is denied his Dexterity bonus to armor class, that attack is automatically a critical threat.