Whirlwind Charge is a 1st level avenger Encounter power that was introduced in the Player's Handbook 2.
Whirlwind Charge
Avenger Attack 1
As you charge your foe, divine light surrounds you in a protective nimbus, then erupts at your foe.
Standard Action
Melee Weapon
Target: One creature
Attack: Wisdom Vs. AC
Hit: 2[W] + Wisdom modifier damage
Special: When charging, you can use this power in place of a melee basic attack. If you charge, you gain a +4 bonus to AC against opportunity attacks you provoke while moving to the target.