Ikora Rey, the Warlock Vanguard, sets up the story of Curse of Osiris in the announcement trailer for the expansion. Here’s what she says:
While we have been fighting, an ancient gate has opened on Mercury. And an army of past and future machines amasses. They intend to reshape the universe in their image. But there is one who has glimpsed this dark future. He was my mentor: Osiris, the most notorious Guardian in Vanguard history.
Once, his dangerous ideas nearly destroyed us, and he was banished. Now he has returned. But will he be a powerful ally, or bring us death?
You are the one thing they have not foreseen. Go to Mercury and find Osiris. Time is not on our side.
Let me just say this one more time…. Curse of Osiris will be available Dec. 5 on PS4, Windows PC and Xbox One. The expansion will be the first of two planned pieces of downloadable content for Destiny 2; together, they comprise the game’s $34.99 Expansion Pass [Digital Code]. The second add-on is scheduled to be released next spring.