I´m Ok with his stats, after all I´ve always thought that he SHOULD be one of the most powerfull wizards in Faeurun....but his starting level
Let me put it this way, if you played Shadows of Amn when it came out, and then almost a year latter got Throne of Baal, you character were probably on the lower twenties in their levels, so making a NPC character one powerful than your protagonist is kind of risky...my wizard was pretty good, and actually had INT of 21 (thanks to the magic tomes of BG 1 & the crazy machine in Watchers Keep) but Jon actually is much better...because of his level. Maybe he should start weakened (as the Nameless one from Torment does) because his ordeal in hell has left him weakened...almost a shade like Sarevok...but having a piece of the soul of the protagonist alows him to gradually recover his former might...