Ace of Blessings

This item drops off of all end-bosses on Heroic difficulties.

Source
This item drops from:
 * Omor the Unscarred in Hellfire Ramparts
 * The Black Stalker in The Underbog
 * Warchief Kargath Bladefist in The Shattered Halls
 * Warlord Kalithresh in The Steamvault
 * Harbinger Skyriss in The Arcatraz
 * Keli'dan the Breaker in The Blood Furnace
 * Warp Splinter in The Botanica
 * Quagmirran in The Slave Pens
 * Murmur in Shadow Labyrinth
 * Nexus-Prince Shaffar in Mana-Tombs
 * Aeonus in The Black Morass
 * Epoch Hunter in Old Hillsbrad Foothills
 * Pathaleon the Calculator in The Mechanar
 * Talon King Ikiss in Sethekk Halls
 * Exarch Maladaar in Auchenai Crypts