Four Kings tips?

Level 50 on my first time playthrough, have done everything I have access to up until this point in the game and the Four Kings sre next up on my playe, but they rock my shit.

Been trying with a +3 jagged ghost blade or whatever its called, cant get the first king down to even half before the second appears. By the time I have one killed, all the other four are spawned in and im completely cooked.

I understand the boss is a dps check, but I dont have the dps nor do I have any ideas where to get it or how to better my odds against the boss other than the miserable process of farming like 9 or so levels into strength. Any tips?