• Amice of Inconceivable Horror
• Item Level 226Disenchants into:
  [Abyss Crystal]: 1-2
• Binds when picked up
  
• Cloth
• Shoulder
• 236 Armor
• +48 Stamina
  +49 Intellect
  +42 Spirit
• Red Socket
  Yellow Socket
• Socket Bonus: +6 Spirit
• Durability 60 / 60
• Requires Level 80
• Equip: Improves haste rating by 62.
  Equip: Increases spell power by 100.
• 

Source

This item drops from Yogg-Saron on hard mode in the 10-man version of Ulduar.

Patch changes

•  Hotfix (2009-05-21): Will no longer have class restriction.
  
• Patch 3.1.0 (14-Apr-2009): Added. 
  

External links

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