Use corrosion to remove armor. Only gargoyles are really hard to penetrate so you have to keep hitting them with ranger. Everyone else becomes vulnerable to fighter after 2-3 corrosions. Just got to level 30 too. Did not reset for a while (only 900 points in perks and 430 ready for next reset), so attack is not that good right now. Still it's possible to progress.
 "Cave Heroes")