Ash-Covered Horn
Drops from Carl Goodup. It doesn't say it on the item, but it can only used on the timeless isle.
The 
Ash-Covered Horn is a toy dropped in Mists of Pandaria that grants a temporary mount exclusively on Timeless Isle.
Guide awaiting review
Purchase from Darkmoon vendor
Visit Carl Goodup at 49.2, 76.4 in Darkmoon Island and purchase the Ash-Covered Horn from his vendor inventory.
Travel to Timeless Isle
Go to Timeless Isle, the only zone where this toy can be activated.
Use the toy
Activate the Ash-Covered Horn from your inventory to summon a temporary Ashhide Mushan mount with 275% movement speed for 20 seconds.
Tips
You can steer the mount but cannot stop it—dismounting requires falling off a cliff or taking lethal damage.
Combine the toy with
Windfeather Plume to increase movement speed to 325%.This toy does not unlock a permanent mount; the learnable version is
Reins of the Ashhide Mushan Beast.The toy cannot be used in battlegrounds.
