Frost Hide Rage is a daily power available to Barbarians at level 15.[PrP:18]
Frost Hide Rage
Barbarian Attack 15
Your weapon becomes icy as you strike. Afterward, the ice spreads over you, shielding you from hide.
Melee weapon
Target: one creature
Attack: Strength vs AC
Hit: 3[W] + Strength modifier cold damage, and the target is slowed (save ends)
Miss: Half damage.
Effect: You enter the rage of the frost hide. Until the rage ends, you gain resistance to all damage equal to your Constitution modifier.