Retaliation Strike

Way of Endurance: 6th, 9th, 13th, and 17th level You learn to turn an opponent's aggression back on them. When you deal damage with a force power or a melee weapon attack, if you took damage since the start of your last turn, you deal an extra 1d6 damage. The damage is the same type as the power or weapon's damage. This die increases when you reach certain levels in this class: to 1d8 at 9th level, to 1d10 at 13th level, and to 1d12 at 17th level.

Granted by Way of Endurance at 13th level.