With the release of Patch 10.2.7 Dark Heart, the final chapter of Dragonflight's storyline is available to play. We played through the questline to bring in all the details! WARNING: Patch 10.2.7 Dark Heart Story Spoilers in this post! The Dark Heart questline starts the moment you first log in for Patch 10.2.7.
Khadgar will send you a message telling you to go to Dalaran to meet him as soon as possible. Khadgar: We are in need of your aid once more, champion.
A mysterious figure moves within the shadows. The Harbinger... Khadgar: Let us speak in the Chamber of the Guardian. I've asked Alleria to meet us there as well.
As we approach Khadgar on the Hall of the Guardian, Alleria Windrunner is there waiting for us, and talking to her will trigger an in-game cutscene version of the 10.2.7 Dark Heart patch cinematic.
You can also talk to Khadgar for a bunch of details on the Dark Heart, the Harbinger and the Radiant Song. > What do we know about the Dark Heart?