I've recently started playing hardcore. There are end game areas that can be farmed depending on your class. I'm using a shield throw barb (one of the awesome new skills) and have been able to farm nightmare Tristram monsters. It's a all about avoiding the center of the map and only pulling one at a time when possible. Shield throw can stun lock the mobs so the danger mostly come from approaching the monsters. If you target them and throw a shield as you run in you can stun them while you dodge their fire attacks. As I don't have a way of penetrating phys immune yet I just start a new game if I run into too many ghosts. I can stun them but can't damage them. You can use this method with a Smiter but it would be tedious and more dangerous as you can only stun lock one at a time. Shield throw will bounce between five targets.

For leveling I used cows. You can open the cow level without having to kill Baal in this mod. With decent aoe damage you can start killing them early but the optimal level to start normal cows is 25. You won't get much xp earlier than that because of your level difference from the cows. Shield throw on its own has enough damage at lvl 20 to farm cows even without a weapon