You hit one enemy, then cleave into another.

At-Will   ✦     Martial, Weapon
Standard Action      Melee weapon

Targets: One creature

Attack: Strength vs. AC

Hit: 1[W] + Strength modifier damage, and an enemy adjacent to you other than the target takes damage equal to your Strength modifier.
    Level 21: 2[W] + Strength modifier damage.

Published in Player's Handbook, page(s) 77, Class Compendium.