• Constellus
• Item Level 239Disenchants into:
  [Abyss Crystal]: 1-2
• Binds when picked up
  
• Mace
• Main Hand
  
• Speed 1.80
• 93 - 298 Damage
• (108.8 damage per second)
• +54 Stamina
  +55 Intellect
• Blue Socket
• Socket Bonus: +5 Spell Power
• Durability 105 / 105
• Requires Level 80
• Equip: Improves critical strike rating by 29.
  Equip: Restores 24 mana per 5 sec.
  Equip: Increases spell power by 587.
• 
• Sell Price: 24 26 86

Source

This item can be found inside Rare Cache of Winter after defeating Hodir on hard mode and inside Gift of the Observer after defeating Algalon the Observer 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