https://www.polygon.com/2018/6/5/17425474/destiny-2-forsaken-gambit-prison-of-elders

In Destiny 2: Forsaken, players will be returning to the Prison of Elders. Destiny’s House of Wolves expansion — which also took place in the mysterious Reef — first let players dive into the Prison of Elders for loot and glory. In Forsaken, the game’s September expansion, the Prison of Elders looks to be making a return as the home of Gambit, a new cooperative and competitive mode for Destiny 2.

In the Forsaken reveal stream, Bungie unveiled Gambit, a new PvPvE mode. Players start the mode being dropped into an area that looks very similar to the Prison of Elders. Across from them is another team of Guardians — real players out there in the world of Destiny.