Part of the Sorcerer's Regalia set:

The set gives these bonuses as more pieces are worn: 2: +8 All Resistances. 4: When struck in combat has a 2% chance of freezing the attacker in place for 3 sec. Can only occur once every 60 sec. 6: Increases damage and healing done by magical spells and effects by up to 23. 8: +200 Armor. Set Details | All Sets

Quest Reward from:

Level	Name	Start	Rewards
60	Saving the Best for Last  (Dungeon) Horde and Alliance Ironforge	Deliana Ironforge	1650 XP
60	Saving the Best for Last  (Dungeon) Horde Orgrimmar	Mokvar Orgrimmar	1650 XP

Disenchants into

Name	Value	Drop%
Nexus Crystal	1 Copper	100.0%