It's different on Tactician difficulty, where the magisters get annihilated and the fire elementals nuke you. Making fire resistance potions and casting ice on them works well. Casting fire and earth not so much, and you might get destroyed if you get close enough to melee them.
I play on tactician/honour mode and I had no problem with that tactic. just need to maintain the high ground and keep them away from you. Kill the ones that get close and CC the ones further away. Spin Web (the polymorph skill) gives you 3 turns of guaranteed CC. Stick it on every char in your group and you should have no issues controlling the battlefield. This is how I did it and I play solo lonewolf (as in, only 1 char) if it works for me it should work for everyone else.
