Valarjar Stormwing

The beating of its wings sound like the rolling of thunder in the distance.

Riding Requirements:

This mount is available to all eligible characters on your account.
Level 10
Apprentice Riding (ground)
Expert Riding (flying)

Source:

Valarjar Strongbox (Paragon reward).
The Black Market Auction House (rarely)

Notes:

There's a small chance of obtaining this mount in a Valarjar Strongbox, which is a 'Paragon'-level reputation reward. To obtain one of these chests you must first reach Exalted reputation with the Valarjar faction in Stormheim, and then continue performing daily activities for them. Every time you earn 10 000 rep with this faction above Exalted reputation, you'll be eligible to receive a Valarjar Strongbox from the Valdemar Stormseeker at Valdisall in Stormheim.