Snake's retreat
rogue attack 19
Requirement: wielding a crossbow, a light blade, or a sling.
Target: one creature
Attack: Dexterity vs. AC
Hit: "6[W] + Dexterity modifier damage."
Effect: When the target makes a melee attack or a ranged attack against you, you can shift 1 square as an immediate interrupt. The target can make a saving throw to end this effect.[PH:124]
Snake's retreat is a daily power available to rogues at 19th level.