I remember creating a 3E NPC called the Minor Mage. He was a Ftr 2 / Wiz 5 / EK 10 or thereabouts who had had his Int reduced to 1. But he had a Belt of Heroism +6 and a +5 Inherent Bonus to Int and managed a +2 Insight bonus too, so he could cast spells up to 4th level. He had metamagic feats aplenty so he could make good use of his high level slots. He just wanted a Wish to reverse the effect.