I would create a magus with the flaws unstructured caster and short-ranged magic and the virtue tethered magic (from HoH:TL) and many virtues and skills that aid him in spont casting (like affinitys, boosed magic, virtues that give you exp like secondary insight, and of course artes liberales and philosophy) and the virtue enduring magic would be good too.
With this you would simply enchant your potions at the beginning of the day with your tethered, spont magic and use them whenever you want.
Combined with Diedne powers (instead of a Verditius which wouldnt gain any benefit from his lab virtues) this char concept could be very cool and powerful.