Computer controlled Mages are limited in their AI, and you, as a Human Being, can easily outwit that AI.
Retreat until the potent spell protections run out. Use an elemental weapon to bypass the Stoneskins. It can be done, I have completed the game( SoA + ToB) with a solo Cavalier. [img]smile.gif[/img]
Oh, and once you get the Cloak of Mirroring... ...
