Blizzard have produced an online comic which actually is rather good (albeit rather "Alliancey"!!), which describes some of the lead-up to Legion.
It has been four years since the dwarf king Magni Bronzebeard was cursed as he sought to protect his world, frozen as a solid diamond statue at the center of Old Ironforge. In our new Legion digital comic, "Fault Lines," he emerges from his crystal slumber with a dire warning of dark times to come. But will his daughter, Moira, be able to set aside the pain of her past to forgive Magni and help unite her people?
We invite you to read and download the free comic here, or experience the action and sound of this tale through the Madefire motion book.
Blizzard have also announced that, during the pre-expansion period, following the patch, there will be a series of events occurring in-game on a weekly basis, each revealing more information:
To clarify, the return of Magni, Khadgar's visit to Karazhan, the Council of Six, the defense of Dalaran and summoning of Alodi events will take place during the weeks leading up to Legion's launch. Each week, more of the story will be revealed.
Players logging in after Legion's launch will see what you see when you start a new character on the beta today. You will progress from the Broken Shore, through the aftermath and introduction of the Illidari, then immediately get a missive from Khadgar telling you that Dalaran is about to teleport.
Players that missed these stories as they were played out in-game over the pre-launch weeks can request to see them from Archivist Elysiana in Dalaran at any time.
(Note that the black indicates a spoiler - so don't highlight it unless you want to see it!)