Smiting Reversal (Combat)Source Agents of Evil pg. 19
Your can withstand the onslaught of holy or unholy forces.
Prerequisites: Power Attack, Toughness.
Benefit: Three times per day after being targeted by the smite attack of an enemy, you can immediately make an attack of opportunity against the target. You gain a bonus on this attack roll equal to your Charisma bonus. If this attack of opportunity hits, you gain a bonus on the damage roll equal to your character level. This attack of opportunity ignores all damage reduction the creature possesses.