Light and Darkness is a 7th level avenger Encounter power that was introduced in the 372nd edition of Dragon (magazine).
Light and Darkness
Avenger Attack 7
As you send a soul upon its final journey, divine energy strikes out from you and your foe in equal measure but opposite character.
Melee weapon
Target: One creature
Attack: Wisdom vs. AC
Hit: 1[W] + Wisdom modifier damage. If this attack reduces the target to 0 hit points, enemies adjacent to the target take 5 necrotic damage and enemies adjacent to you take 5 radiant damage.