Yeah finally down after like 7 hours with 481 ilvl. with 30sec left on the enrage, I avoided the Doom debuff the first 1-2min with charge and port so I did not need any purification pot.
The fel puppies are the toughest thing to deal with imo, when you learn how to deal with them you have this fight! And letting your pit lord tank the Demon lords will make the fight so much easier than if you banish/fear/kill them.