Long range sniping with a bow is the way I dealt with them. I can usually one shot them this way.

If I couldn't do that (terrain, ect), I'd kite Lox or something to them, or kite them to a place I could safely plink at them. Perched on a stone with an edge I can hide behind is best. Always scout out for a place first, then kite.

Barring everything else, a buckler and dodging. There is a lag between them firing their poo at me, and loading the next. Kite them a bit away. Usually causes one to lag behind. Turn, dodge poo, run up and beat the hell out of the closest one. I can usually off one with just one round of beatings. Run away before poo, rinse repeat.

Once you've cleared out the pit, they usually take some time to respawn. Plenty of time to drain and get what you need. Even if you're slow, like me, in doing it all.

All that said, I feel they are a bit OP at the moment. Poison and slow, combined with their firing range and agro range, is a bit too much. Something needs some pretty big adjustment on them. Maybe even some abilities removed.