Speak with Nathanos Blightcaller in Orgrimmar.
The world's soul is secure... fer now. I can hear Azeroth again, though her voice is still weak. The elementals on the surface above have calmed down. Even using just a fraction of its power, the Heart of Azeroth brought stability tae this place. Ye need tae return tae Orgrimmar and inform yer allies what transpired here. Remind them that no matter what happens in their war, our world must be saved. We'll speak again soon, <name>. The battle fer Azeroth has only just begun.