Warlock Utility 6Chaos Armor

Power flows around you, girding you against the elements and lashing your enemies.

Daily        Arcane, Elemental, Varies
Minor Action      Personal

Effect: Choose acid, cold, fire, lightning, or thunder. Until the end of the encounter, you gain resist 10 to the chosen damage type. In addition, whenever an enemy hits you with an attack during your turn, one enemy within 5 squares of you takes damage of the chosen type equal to your Constitution modifier.

Published in Heroes of the Elemental Chaos, page(s) 103.