In my mind the non dualed from a fighter mages are silly. Simply because the fighter class brings so much to the table from the breakfast forward. And the game seems to be made with this in mind.
In IwDinBG2, cases can be made that the single class mage is even worse, specially when mod kits are inserted to the mix.
The Web is a good spell, but a lone mage can't make it work, so you have to have more than one magic caster, be that a bard, thief-dual-or-multi or a cleric with battle magic... and a couple of archers.
Yep, Jarno Mikkola. my Mega Mod FAQ. Use of the BWS, and how to use it(scroll down that post a bit).
OK, desert dweller, welcome to the sanity, you are free to search for the limit, it's out there, we drew it in the sand. Ouh, actually it was still snow then.. but anyways.