This mount is a rare drop of the heroic-only boss, Anzu, in Sethekk Halls.
It has a higher drop rate than other rare mounts at ~2%.
Awards the Feat of Strength Reins of the Raven Lord.
This mount can appear on the Black Market auction house.
The reason for the higher drop rate is because back in The Burning Crusade era, this boss could only be summoned by druids who completed the quest chain for Swift Flight Form, which made the boss alone quite rare.