Not actually all that terrible - I'm sure he will be topped, but just to start us off:
Tempestus of Tytalus
Stamina +3
Affinity: Auram
Affinity: Creo
Puissant Creo
Puissant Auram
Minor Magical Focus (Lightning)
Mastered Spells
Arcane Lore
Cr: 12+3
Au: 12+3
Penetration 4 (Spec: Auram)
Incantation of Lightning (Mastery 4)
Mastery Abilities (Multicasting, Penetration, Magic Resistance, Your Favorite) - last one can be varied depending on concept.
Casting Total of 52 for Incantation of Lightning.
Penetration ability is considered 4 higher due to mastery => base penetration 31+die without penetration multipliers and ignoring Aurae.
Throws 5 Bolts of Lightning every round and is unlikely to ever tire out.
Common variant involves the ability to turn into a bird (change house to Bjornear or take Skinchanger or Shapeshifter), in which case a combination of Virtues and Masteries are taken to allow for Silent Casting with no gestures required. Deft Auram is popular for this.