http://www.pcgamer.com/destiny-2-curse-of-osiris-officially-revealed/

The Destiny 2 expansion Curse of Osiris was revealed, intentionally or otherwise, on the Microsoft Store in September. Now, thanks to a trailer released during the PlayStation livestream today at Paris Games Week, we finally got a look at what it's all about. 

The Red Legion may be out of the fight, but that doesn't mean an end to the bad guys of the universe. So it is that we end up with an army of the robotic Vex pouring through an ancient gate on the planet Mercury, and only one hope of stopping them: Osiris, the most notorious Guardian in Vanguard history, who was banished centuries ago for "dangerous ideas" that nearly destroyed the Guardians. But does he return as friend or foe?