Counter-Attack

Effect: 

Once per round when the escalation die is even and an enemy misses you with a natural odd melee attack roll, you can make a basic melee attack dealing half damage against that enemy as a free action. (The attack can't use any limited abilities or flexible attack maneuvers.)

Adventurer Feat: 

Your Counter-Attack attack now deals full damage.

Champion Feat: 

You can use Counter-Attack once per turn instead of once per round (in effect, you're free to Counter-Attack once per enemy turn).

Epic Feat: 

You can now use Counter-Attack when the escalation die is 3+.