If there's any challenge in particular, I can try to say how I did it. I've finished NG+, but not NG++.

I also started a long general strategy thread, but sometimes I've gone back and said the opposite of what I said earlier.

If you have a controller, and you grind enough, and get blueprints and a lot of base stats, then you should be in decent shape eventually. Slowing down to get Tier 2 gear makes it easier to start the tower, but I think it won't spawn in the main castle area. Tier 3 blueprints seem to not spawn every time and only in the two hard areas, but I found that the Guardian set seems like the best gear you can get outside of NG+.

It takes getting used to it. Once the first area becomes a sure clear, you can pay attention to class/spell combos and stick to what that class is good at - Shinobi can sometime one-shot things in harder areas, and Barbarian or Paladin can grind the first two areas forever. Miner with the upgraded special can see where all the loot is. Sometimes "?" is a boss who drops a blueprint, so if you manage to find a miniboss as miner, you can lockdown and kill the boss with someone who actually does damage. (But just getting there can be pretty hard with that class...)