Vigorous Strike is an encounter power available to the Barbarian class at level 17.[PH2:58]
Vigorous Strike
Barbarian Attack 17
You strike your foe with a mighty assault that bolsters you against attacks.
Melee weapon
Target: one creature
Attack: Strength vs AC
Hit: 3[W] + Strength modifier damage, and you gain temporary hit points equal to one-half your level.
Rageblood Vigor: The number of temporary hit points equals one-half your level + your Constitution modifier.