Cleric Help (can't beat Arc, Sewer of Horrors)
You might benefit from reading over the game mechanics on how the game fights. Instantly over-powering clerics with high levels and top tier gear won't help unless the gear is right for the situation and the character build is solid.
Clerics, as a class, hold all the low level records (lowest level to beat arc, lowest level to complete Sewer of Horrors etc). When built right and played right, Cleric's are powerhouses. Play them like a warrior that can heal and you're doom to frustration.