I'm lvl 73, I switch between the lightning staff and the lightning greatsword depending on the boss. I'm on a 8 star difficulty map with more than 80k gold. For the last two stars, I didn't bother collecting gold nor items. Just picked the easiest path through the map and cleared it since I knew I couldn't grow more.
Totally, this game can get blazingly fast if you have the right build in the right area. Make sure to have eyedrops on hand!