Part of the Frostfire Regalia set:

The set gives these bonuses as more pieces are worn: 2: Reduces cooldown on your Evocation by 1 minute. 4: Gives your Mage Armor a chance when struck by a harmful spell to increase resistance against that school of magic by 35 for 30 sec. 6: Your damage spells have a chance to cause your target to take up to 200 increased damage from subsequent spells. 8: Your damage spells have a chance to displace you, causing the next spell cast to generate no threat. Set Details | All Sets

Quest Reward from:

Level	Name	Start	Rewards
60	Frostfire Robe  (Raid) Horde and Alliance Naxxramas	Archmage Angela Dosantos <Brotherhood of the Light> Eastern Plaguelands

Disenchants into

Name	Value	Drop%
Nexus Crystal	1 Copper	100.0%