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.
Ooh, I’ve been trying to do this with same champion and challenges for a small while. Trying to get both the “3 or more challenges” and “beat final boss with badder bosses and all demon spawners enabled” badges. Failed each time, including twice getting to 25th floor but failing to beat Yog-Dzewa. Maybe I should be less ambitious and only try to get one badge at once…