• Arcanum of Burning Mysteries
• Item Level 80Disenchants into:
  Not disenchantable
• Binds to Battle.net account
• Requires Level 80
• Requires Kirin Tor - Revered
• Use: Permanently adds 26 Intellect and 20 critical strike rating to a head slot item.
  
  Enchanting the item causes it to become soulbound.
• Sell Price: 37 50
• Vendor 150

Source

This item is a reputation reward; you must be revered with the Kirin Tor to buy it from Archmage Alvareaux <Kirin Tor Quartermaster> for 150.

Notes

• According to various web item DBs including Battle.net, there is a version of this item which doesn't have a rep req. on its tooltip, but maybe it doesn't show up if you don't have the right rep.

Patch changes

• / Patch 4.0.1 (12-Oct-2010): Effect changed from "Use: Permanently adds 30 spell power and 20 critical strike rating to a head slot item. Does not stack with other enchantments for the selected equipment slot." to "Permanently adds 26 Intellect and 20 critical strike rating to a head slot item." 
  
• Patch 3.3.0 (08-Dec-2009): Added. 
  

External links

Reputation required

• Battle.net (EU)
• Wowhead
• Thottbot
• WoWDB

No reputation requirement

• Battle.net (EU)
• Wowhead
• Thottbot
• WoWDB