4SRD > Doppelganger Trick
Doppelganger Trick: ou have the doppelganger trick Doppelganger racial ability.
Your feint tricks a foe into giving you an advantage.
(Swift Action, Melee range within 5 feet)
Once per encounter, you can make a Bluff check opposed by one target's passive Insight. If your check succeeds, you gain combat advantage against the target until the end of your next turn.