The Destiny 2 Fourth Horseman has arrived virtually unchanged compared to the Destiny 1 original. It's a quad-barrel arc Exotic shotgun with an absurd fire rate, equally absurd recoil, and pretty dang impressive DPS. Think of it as the shotgun version of The Last Word - a close-range face-melter with damage that drops off like a piano off a cliff. That said, it's fun to use and can utterly delete Champions under the right circumstances, so you really should pick it up. To that end, here's how to get the Fourth Horseman in Destiny 2.
To start the quest, you'll need to visit Zavala, who will tell you to hit up his vault in the Tower. The path to this vault is similar to the one for the Leviathan Exotic quest, which is to say extremely windy and buried. Here's a GIF to help you along:
Once you start the quest, it's pretty much just kill the dudes and find the things from there. Here are the remaining quest steps complete with minor pointers:
- Complete Public Events on Mars. Heroic Public Events grant the most progress, but Escalation Protocol completions also count and are much more readily available. Farm EP and complete whatever normal Public Events you see in the meantime.
- Open Cabal chests on Mars or kill Psions. The chests are the way to go here. Equip a Ghost Shell with Treasure Hunter or a Mars chest finder, run around the northern portion of Mars (which generally has more chest spawns), and open 'em up. If you don't have a relevant Ghost shell, searching for chests manually will still be faster than killing Psions.
- Complete Public Events and Patrol activities in the EDZ. Heroic Public Events grant the most progress, so check your map for any active Public Events and complete loose Patrol objectives in the meantime.
- Clear the Legendary Quarry Lost Sector and open the chest at the end. You can only complete this step while the Legendary version of the Quarry is available, so you may need to wait depending on when you start the quest.
To get the Exotic catalyst for the Fourth Horseman, complete Seraph Tower Public Events and Legendary Lost Sectors until it drops. It's a random drop, and quite rare at that, so this may take a while.