Let me offer these words...
First of all, I would recommend that you just send your tanks in and open up a can o' whoop-ass on 'em. They won't last long.
However, if you must use spells, there is a strategy that is often overlooked. You can cast "Magic Resistance" (*not* Lower Resistance) on the enemy. What this does is grants the recipient MR equal to 2% times the level of the caster (i.e. 10th level mage casting MR on someone grants 20% MR to the recipient). Now, the way this helps you is that it will actually
lower the recipient's MR if it was higher to begin with. For instance, utilizing the above example, if the Mage listed above were to cast MR upon an enemy with 80% MR...they no longer have MR of 80%, it is now set at 20%! Then if you cast a Lower Resistance on top of that (not sure if you can do that though...), they're toast!
