Ashes of Al'ar

The Ashes of Al'ar grant their wielder the ability to summon an epic phoenix mount. The item has a very low drop chance.

Source
The Ashes drop from Kael'thas Sunstrider in the Eye.

It can also be found listed on the Black Market Auction House by Mei Francis, for the starting bid of.

Mount Journal
''Al'ar was the beloved pet of Kael'thas Sunstrider, who often boasted that death would never claim it. Perhaps he was right.''