I just added a Wand of CLW to Corund's equipment.
I think our best strategy in a fight is to hit-and-run. Certainly each of our characters has the ability to get out of Dodge and regroup, to simply come back again and attack again. Dropping a few summoned shadow monsters or an acid fog is a nice way to soften anyone up. If we can't cut and run, Jonas can tank quite nicely, and Cassandra and Corund can skirmish or support. And quite frankly, with good stealth skills, they should be able to bypass many useless fights and strike where it counts most.