You ward yourself with a mantle of flame.

Encounter   ✦     Arcane, Fire
Immediate Interrupt      Personal

Trigger: You are hit by an attack

Effect: Until the end of your next turn, you gain a +1 power bonus to all defenses, and any creature that hits you with a melee attack takes 1d6 fire damage.

Published in Player's Handbook 2, page(s) 140.