I think I finished one or two other quests but they're pretty long and have a bunch of steps. I barely got my guys up to level maybe 6 or so. In the basement you can blow through the skeletons for lots of xp. Think you mage has a fire AE that will just wipe em out pretty easily. Another thing to remember for your casters is that you can change what spells you have "learned" for them. So if you pick some spells that turn out lame, at the trainer you can just untick those spells and pick others - there's no cost for that.

It's a friggen hard game, hah.