Meet Merithra at the Temple of Elune in Val'sharah.
The green dragonflight calls for aid. The Emerald Dream, which they have watched over for eons, has been invaded by terrible creatures of the Void.
Merithra of the Dream is attempting to combat the threat, but she cannot do so alone. If you seek to empower the Heart of Azeroth with the strength of the green dragonflight, you must first help Merithra save it.
Meet her at the Temple of Elune in Val'sharah, and assist her however you can.