https://www.gamespot.com/articles/destiny-2s-first-season-2-faction-rally-event-anno/1100-6455474/

Destiny 2's first Season Two Faction Rally event has been announced--and it starts soon. As with the previous events, you start by aligning with a faction--New Monarchy, Future War Cult, or Dead Orbit--and then earning engrams from your faction. The group that collects the most (Dead Orbit and New Monarchy won the previous events) will get to pick up special rewards at a discounted rate.

For this event, there is exclusive gear (including ornaments, weapons, and shaders) for each faction. If you're in the faction that wins you can get a faction-specific weapon for 1,000 Glimmer, while the losers have to pay 50,000 for it.