https://www.polygon.com/2017/12/8/16752776/destiny-2-crucible-prometheus-lens-crucible-pvp-bungie

Destiny 2’s PvP mode, Crucible, is all about the Prometheus Lens currently. The overpowered and straight-up busted exotic trace rifle added with the Curse of Osiris expansion is the go-to weapon in competitive multiplayer, thanks to its enemy-shredding abilities. (Bungie promises that a fix is in the works.)

So if you want to stay competitive in Destiny 2’s Crucible over the next few days — including in Trials of the Nine, which, yes, is still on this weekend — you’re going to need a Prometheus Lens of your own. Fortunately, weekly vendor Xur is selling the exotic trace rifle for 29 Legendary Shards a pop.