You raise an aegis in your ally's defense, infusing the shield with elemental energy to help defend against certain attacks.

Daily   ✦     Arcane
Immediate Interrupt      Close burst 10

Trigger: An enemy you have marked attacks an ally.

Target: One ally in the burst.

Effect: Choose a damage type: acid, cold, fire, lightning, or thunder. Your ally gains resistance to that damage type equal to 5 + your Constitution modifier until the end of your next turn.

Published in Dragon Magazine 367, page(s) 56.