Travel to Grim Batol and track down Axtroz, drake champion of the Red Flight. Destroy him and take his skull. Return the skull to Emberstrife.
"It was over the mountains of Grim Batol that our Father raged against the combined might of the Aspects. The cowardly act of the betrayer, Alexstrasza, bought the other Aspects enough time to escape from Father's wrath.
Sssuch a shameful act...
The Red Flight now guards Grim Batol, their lieutenant, Axtroz, must be destroyed. Return the skull of Axtroz to me. For Father, whelp!"