Before its launch, Bungie held a livestream event on Twitch that covered numerous areas of new features coming to the "Curse of Osiris" expansion. An introductory cutscene featured Osiris and his Ghost, Sagira, as they explore a Vex reality engine called The Infinite Forest (not technically part of the Vault of Glass, Bungie today confirmed). Players will also be able to travel to the Lighthouse, the social space on Mercury that was previously exclusive for players who had gotten nine consecutive victories during a Trials of Osiris run.
While you were gunning your way through the campaign, "past and future" machines flocked to an ancient gate on Mercury to create an army with the goal of restructuring the entire universe as they see fit.
Destiny 2 won't get a new Raid, per say, but a Raid Lair instead. Beyond that initial bummer is a pretty cool idea, though: with both of the Season Pass expansions, Bungie plans to add a new "Raid Lair" to the Leviathan Raid.
Bungie raised the overall player and power level to 25 and 330, respectively, so you'll need to make sure that you meet the requirements to try the new endgame activities. These will take place in the same general location (in this case, on a giant, planet-eating ship) but offer new challenges, puzzles, places, and even a new end boss for players to overcome in a somewhat shorter overall experience.
Bungie reveals first details for Destiny 2's Curse of Osiris expansion
After the developers explored the Lighthouse, they went outside into the fields of Mercury and showed off the new patrol area, which will be filled with activities and events like Lost Sectors and Public Events. In the time since, it only saw a new raid once per year, and the common wisdom was that Bungie was too ambitious to want to do more than that. It will have a Prestige mode, if you're the tough type.
The stream also detailed a bit of the story to expect with Curse of Osiris.