Stunning Fist (Mythic)
With greater potency and frequency, your fists stun those who stand against you.
Prerequisite: Stunning Fist.
Benefit: The DC of your Stunning Fist increases by half your tier, and you can use Stunning Fist multiple times during the same round. As a free action, you can expend one use of your mythic power to use Stunning Fist without spending one of your daily uses of the feat.
Source: Mythic Adventures, p. 75