When you can't run, you crawl, and when you can't crawl you find someone to carry you.
The mount is mailed in-game to the character you select from Master Handler Sylvester. With the item is a unique letter written up as a shipping manifest:
Heart of the Nightwing
Grasped tightly and clutched to one's breast, this enchanted heart of volcanic glass can transform the bearer into an Obsidian Nightwing.
Prior to its being removed as a reward for Recruit-A-Friend, this mount was one of only two mounts which allowed the player to transform into a flying mount capable of carrying another player on their back, the other being the [Vial of the Sands].
In the past, some players have reported that this item can appear as an extremely rare find during Archaeology, although this was possibly due to a glitch.