If you're looking for a powerful build than 12/8 would be the best, as you'd get many Palemaster abilities by level 20 (if you make it that far) but you'd still get spells up to 6th circle, and you could take Eschew II to knock out all your spell components. However I've recently taken a liking to RP affecting your characters development all the way, so perhaps he'll want to go 15/5, or 10/10. But in the end it's up to you.