Imperiling strike
rogue attack 7
Melee weapon
Requirement: wielding a light blade
Target: one creature
Attack: Dexterity vs. Fortitude
Hit: "1[W] + Dexterity modifier damage, and the target takes a −1 penalty to AC and Reflex defense until the end of your next turn.
"Brutal Scoundrel: The penalty to AC and Reflex defense is equal to your Strength modifier."[PH:121]
Imperiling strike is an encounter power available to rogues at 7th level.