• Chestguard of Insidious Intent
• Item Level 226Disenchants into:
  [Abyss Crystal]: 1-2
• Binds when picked up
  
• Mail
• Chest
• 1314 Armor
• +88 Stamina
  +68 Agility
  +59 Intellect
• Yellow Socket
  Yellow Socket
• Socket Bonus: +6 Agility
• Durability 140 / 140
• Requires Level 80
• Equip: Improves hit rating by 60.
  Equip: Increases your armor penetration rating by 67.
  Equip: Increases attack power by 196.
• 
• Sell Price: 13 7 37

Source

This item drops from Yogg-Saron in the 25-man version of Ulduar.

Patch changes

• Patch 3.1.0 (14-Apr-2009): Added. 
  

External links

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