You study the enemy, looking for a gap in his defenses. Only when you find it do you strike.

At-Will   ✦     Martial, Weapon
Standard Action      Melee or Ranged weapon

Requirement: You must be wielding two melee weapons or a ranged weapon.

Target: One creature

Attack: Strength + 2 vs. AC (melee) or Dexterity + 2 vs. AC (ranged).

Hit: 1[W] + Strength modifier damage (melee) or 1[W] + Dexterity modifier damage (ranged).
Increase damage to 2[W] + Strength modifier damage (melee) or 2[W] + Dexterity modifier damage (ranged) at 21st level.

Update (11/23/2009)
On the Hit line, add “+ Strength modifier” between “damage” and “(melee).” Also on the Attack line, add “+ Dexterity modifier” between “damage” and “(ranged).”

Published in Player's Handbook, page(s) 105.