Circle Step (Martial Arts Maneuver)
From D&D Wiki
Step into the path of the strike, and move to the side of the striking limb. If you do so, you take his side, and the enemy will surely show you an opening.
Level: Reactive 1
Description: You may initiate this maneuver in response to a melee attack made against you as long as the opponent is the same size as you, or maximally one size larger or smaller. You gain a +4 bonus to AC against that attack. If the attack misses, you gain a +2 bonus on all your attacks against that opponent next round. This maneuver must be initiated before the enemy's attack roll is made.