Vicious slash
rogue attack 15
Requirement: wielding a crossbow, light blade, or sling
Target: one creature
Attack: Dexterity vs. AC
Hit: "3[W] + Dexterity modifier damage. The target takes a -2 penalty to attack rolls and ongoing 10 damage (save ends both)."
Miss: "Half damage, and the target takes a -2 penalty to attack rolls until the end of your next turn."[MP2:66]
Vicious slash is a daily power available to rogues at 15th level.