Bungie said the story is created to dive deep into Destiny lore, focusing on Osiris and, more specifically, the Vex and their true intentions for the universe. It's unclear if this includes the Legendary mod bonus or not, but we do know the base level cap has been raised to 25. No exact release date for this new Raid was given.
Oh hell yeah. Bungie didn't give many details on the stream, but all you need to know is in the header there.
This was the first out of three streams for the Curse of Osiris Reveal. As mentioned by Ikora, it is unclear if Osiris will serve as a useful ally or contribute to the downfall of the universe. Players who purchased the expansion pass will have access to Curse of Osiris as well as the unnamed second expansion slated to release next Spring. 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.
Curse of Osiris was revealed at the tail-end of October alongside a new trailer.
Taking place after the events of the main Destiny 2 campaign, your Guardian is dispatched to Mercury to find the greatest Guardian who ever lived, Osiris. Previously set at 305, the new Light level has been confirmed to raise to 330. Inside the Infinite Forest are "trees" which are really giant monuments that will allows us to see different times, future and past. Let's talk about Raid Lairs. Raid lairs are also less of a time commitment for players than full raids. You also do not have to play the original raid in order to play the Raid Lair. It isn't a new social space, but it's also a bit more than an office for redeeming planetary tokens. There will also be an even more challenging prestige mode as well. Heroic strikes, which were in the first game, are returning with the DLC.