• Breastplate of Undead Slaying
• Item Level 63Disenchants into:
  [Large Brilliant Shard]: 1 (99.5%)
  [Nexus Crystal]: 1 (0.5%)
• Binds when picked up
  
• Plate
• Chest
• 657 Armor
• +20 Stamina
• Durability 135 / 135
• Requires Level 58
• Equip: Increases attack power by 81 when fighting Undead.
• 
• Sell Price: 3 60 57
• Battlegear of Undead Slaying (3 pieces)
• [Bracers of Undead Slaying]
  [Breastplate of Undead Slaying]
  [Gauntlets of Undead Slaying]
• (3) Set: Increases your damage against undead by 2%.

Source

Once dropped from bosses during the Scourge Invasion. However, it is no longer obtainable.

External links

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