As Hyjal Burns
Fly to Hyjal using Aronus and speak to Ysera once you're there.
Description
<name>! We've heard much about you and your previous accomplishments.
It is good that you've come here just as Azeroth finds itself in a time of great need.
Deathwing's minions are attacking Hyjal and seek to bring the destructive Ragnaros back into our world.
Aronus will take you to join Malfurion's forces in Hyjal. Lend them what help you can.
Aronus located just behind and to the left of Emissary Windsong. Make certain to have your sound enabled; Aronus' emotes are voice-acted. As is Ragnaros' emote, come to think of it, but it is only one line.