Safe bet
rogue attack 27
Requirement: wielding a crossbow, a light blade, or a sling.
Target: one creature
Attack: Dexterity vs. AC
Hit: "4[W] + Dexterity modifier damage. If the target makes an attack before the start of your next turn, you can shift a number of squares equal to your Dexterity modifier and make a basic attack against the target as an immediate interrupt."[MP:86]
Safe bet is an encounter power available to rogues at 27th level.