The full array of pre-expansion events are now live in World of Warcraft. However, the one that matters to most players is the Demon Invasion. This is a series of repeating scenarios on a (for now) four-hour timer, but participants below Level 100 can participate due to scaling technology being implemented. What this means is that this event is not just good for gearing alts at the cap, but to level up alts below the cap really fast; if you're going to change to a new class in Legion, and it's not a Demon Hunter, this is the time to reroll and get ready. I'll embed WOWhead's video of the Azshara invasion as well as videos by Asmongold and Bellular on how to level alts efficiently. Enjoy, and make the most of this opportunity. Here is WOWhead's guide.