Panther Claw
You unleash a rapid series of blows on foes that attempt to attack you when you move.
Prerequisite: Wis 15, Combat Reflexes, Improved Unarmed Strike, Panther Style.
Benefit: While using Panther Style, you can spend a free action, instead of spending a swift action, to make a retaliatory unarmed strike. You can make a number of retaliatory unarmed strikes on your turn equal to your Wisdom modifier.
Source: Ultimate Combat, p. 112