The entirety of World of Warcraft: Legion has been building up to a fight inside of the Tomb of Sargeras. It’s the nexus of the eponymous Legion invasion, and it’s the obvious destination for Azeroth’s defenders to make a final stand against their enemies. The good news is you’ll get your chance to fight through it on June 20th, assuming you’ve got a Normal raid group or higher ready to go. Normal and Heroic difficulties are opening on the 20th, with Mythic and one wing of Raid Finder difficulties opening a week later. If you’re going to do the whole thing through LFR, you’ll have to wait until August 8th for the full opening.
So what will you be doing until then? Well, perhaps you’ll be handling the death of Chromie. Everyone’s favorite bronze dragon is going to die, you see, but the nice part about being able to travel back and forth through time is that you can always do something about what will be happening. Since Chromie has somehow seen her death coming in the wrong manner (she knows how she’s supposed to die, after all), players will have to travel back and forth through time to save her life. For now, anyhow; when you can see the future, you’re not under many illusions about your immortality.
