You excel at approaching an opponent from an unexpected direction to deliver deadly attacks. As you approach your foe, you duck and weave to confuse his defenses. Alternatively, you draw a weapon and make a quick attack that surprises your foe.
Prerequisites: Dex 13, Dodge, base attack bonus +12.
Benefit: You can designate one specific foe as the target of this feat as a free action. If neither you nor the target threatens each other at the start of your turn, you gain a +2 bonus on melee damage against that target during your turn.
Source: Player’s Handbook II, page 77.