Fatal Strike is an encounter power available to the Barbarian class at level 23.[PH2:59]
Encounter ✦ primal, weapon
Standard Action
Melee weapon
Target: one creature
Attack: Strength vs AC
Hit: 4[W] + Strength modifier damage, and the target cannot regain hit points until the start of your next turn.
Rageblood Vigor: The attacks deals extra damage equal to your Constitution modifier.