The Revenge of the Cartels event for Borderlands 3 introduced some incredibly powerful Legendary weapons. Quite a few of them are in the top tier of their class, and we definitely worth getting before the event wraps up.
To get your hands on them, you need to go and talk to Maurice at Sanctuary, and he will send you on the hunt for Cartel members. There are a number of different farming opportunities for these weapons. The first comes when name characters from the Cartels spawn in your game after you kill Cartel members. The second is at the Villa Ultraviolet, as you try to hunt down and kill Joey Ultraviolet.
|O.P.Q System||Assault Rifle||Josie Byte, Franco Firewall, and Joey Ultraviolet|
|Nopewpew||Assault Rifle||Roaster, The Tenderizer, and Joey Ultraviolet|
|Grease Trap||Pistol||Roaster, The Tenderizer, and Joey Ultraviolet|
|Yellowcake||Rocket Launcher||Fish Slap, Tyrone Smallums, and Joey Ultraviolet|
|Iceburger||Shotgun||Roaster, The Tenderizer, and Joey Ultraviolet|
|Needle Gun XXL||SMG||Josie Byte, Franco Firewall, and Joey Ultraviolet|
|Firewall||Shield||Josie Byte, Franco Firewall, and Joey Ultraviolet|
|Watson||Shield||Fish Slap, Tyrone Smallums, Joey Ultraviolet|
|Fish Slap||Grenade||Fish Slap, Tyrone Smallums, Joey Ultraviolet|
Joey will always have two random NPCs from the above list with him for the final fight. If you want to farm those two characters for drops, just let Joey kill you after you take them both out. You will respawn near the fountain, and can just drop down the tunnel and start the fight all over again.
It is a very effective way to farm these weapons but will cost a lot of money, so make sure you buy any extra ammo or backpack space you might be able to afford before you start doing it.