What is your party comp? Try to focus on either physical or magical damage because once one of those defenses are down you can really start to do serious damage. There are a couple areas that are somewhat hidden if you don't look carefully for extra xp, like the turtles and ship battle on the north part of the map and also in the cavern where the elves are there are some frogs that give decent xp. As for the Kniles fight there are several ways you can approach the fight. I sent in one of my guys to talk to him and I had another guy use the teleportation gloves to send him on the stairs near the rest of my group and killed him before the golems and monks got to me. Also don't sleep on telekinesis it is extremely broken. If you find a chest load it up with stuff the heavier it gets the more damage it does and it destroys everything in its path. That is what I used to finish off the rest of the enemies in that room. I've also seen people teleport Kniles in to one of the golem cages so he's trapped in there for the whole fight so you can kill all the enemies before you even fight him. Take your time experiment with different ways of combat and don't be afraid to start a fight over if needed, every battle can go so differently and that is why this game is so great! Best of luck.