PVP: Nightstalker with Trapper tree and Gemini Jester, Arcstrider with Arc Grenades and Raspberry vest or Skip Grenades and Shinobu's Vow, Gunslinger with Foetracer and sixshot tree. PVE: Nightstalker with Trapper tree and Orpheus Rig, Arcstrider with Raiden Flux and dodge tree, or Gunslinger with critshot tree and Celestial Nighthawk.
Gemini Jester, paired with the Trapper tree, makes you functionally invisible for a few seconds and shuts down the radar of any goober unfortunate to be close by.
Raspberry vest immediately refreshes your Arc Grenade if you get a kill with it, and slightly upgrades arc grenades.
Shinobu's Vow gets you a second Skip Grenade.
Foetracer lets you chase down anyone you targeted in the last coupla seconds, which is great if someone starts running from you or flanking you. And most people ignore the status effect that lights up when you're tracked.
Orpheus Rig gets you some Super energy back for anyone tagged by the super, and Trapper tree gets you extra health and other things for every target killed while snared by the super. Hit a large enough crowd and you instantly get your super back.
Raiden Flux grants you extra Super running time for every kill scored with the super. You hit someone over the head with the zappy stick, and you keep going. Wade into a crowd, and you're a pain train, no brakes.
Celestial Nighthawk grants you just one shot from the Golden Gun, but it's one hell of a shot. It can melt a Lost Sector boss faster than you can say Cayde Six. You're still fucked if you miss.