You use a nearby ally to gain advantage with your attack.

At-Will   ✦     Martial, Weapon
Standard Action      Ranged weapon

Target: One creature

Attack: Dexterity vs. AC. If two or more allies are adjacent to the target, you gain combat advantage against the target with the attack.

Hit: 1[W] + Dexterity modifier damage. Increase damage to 2[W] + Dexterity modifier at 21st level.

Published in PH Heroes: Series 1.