It took me a long time to finally make it! Swarm intelligence + hostile champions + badder bosses, with a sniper.
I was lucky to get a projecting bow and a brimstone armor (plate). I don’t know if I’d have survived the burning fist + dark fist combo without it.
the bow upgrades itself at every 5 levels
+1 at lvl 5, +2 at 10 and so on