Follow Nxla's advice. Everything (s )he said is true about Fighter/Mages. You might just want to increase your CON to 11, to get more Fatigue and faster regeneration of it.
Force Screen & Haste are the winners, coupled with Fireflash vs groups & Desintegrate vs pesky elementals/golems.
Maybe Heal & Greater Heal, if you don't keep Virgil around, or want to keep him alive.
Magic Resistance is explained pretty clearly in the manual. Read up on it, and feel free to ask any questions about it if it isn't clear. (I say this because I'm not sure about the details myself, and I'm not at home to reference my own manual.
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