Mille Marteaux
Empress of Light
Without killing it? Good luck. They don't even have defense, I'm not sure what you'd hope to accomplish with it.What about applying ichor to the green slime?
Wrong. Players have a MUCH smaller invincibility window when attacked by another player. You can see it yourself by damaging yourself with exploding bullets. The window is somewhere around a fourth of what it usually is, and last I remember Cross Necklace has no effect whatsoever.Also, a tip for PvP: players have the invincibility timer that they normally have, while mobs have none (unless they're hit by a piercing attack, so as to prevent them from taking basically infinite damage). Thus, faster attacks like the Chain Gun or Megashark will deal one of their base damage every 1.5-3 seconds, depending on whether the Cross Necklace is in use. Thus, a hard-hitting weapon like the Tactical Shotgun, Sniper Rifle or Daybreak is the way to go.
I don't see why you'd even call Tactical Shotgun "hard-hitting' when comparing it to the sniper rifle, though. If you wanted wide area damage that hit hard, you'd use Rocket III. Or Daybreak. Or Last Prism.
There's a reason most PVP is done on non-combat modes without endgame gear nowadays instead of lunar tier. Even Titanium Armor Paladin's Hammer days were pretty bad, but at least you could get away from that.