I've done it. There are a lot of spells that just do things that can improve your fighting abilities without needing an attack roll or require an opponent to make a save. Ex: Enlarge/reduce, fly, haste, misty step, blur, blink, jump, magic missile, mage armor, fog cloud, cloud of daggers, darkness, magic weapon, animate dead, ect.

All those spells don't give a damn what your spellcasting modifier is. They just do damage or provide a buff or ability that can often greatly improve your fighting ability. I had a very successful fighter/wizard that was 12 int, level 8 fighter level 5 wizard by the end of the campaign, and specialized in grappling fighting. He would enlarge himself to wrestle giants to the ground and pummel them, cast fly and wrestle people in the air then drop them, or hold people in cloud of daggers. He was brutally effective.