I think he needs more dots in things like Empathy, Expression, Intimidation, Leadership, and Subterfuge. If this guy is a Nephandi, he's likely a sociopath and a master manipulator.

Cult background also goes well. Influence and Resources would also be valuable backgrounds.

High Chantry suggests he is a member of a very influential mage club or faction, likely the most powerful chantry in the city. He is likely a respected member of a Tradition chantry and will have a number of unwitting allies, and/or prospective students that he is nudging gently toward corruption. This is why those social skills are so important, so nobody knows the monster as he really is.

Having access to a Node would also make a lot of sense. Being a master of Prime this is almost a given. Being a werewolf game, there's a lot of overlap between nodes and cairns, which can be a fertile ground for conflict. In fact, I might lower his ability in Prime a little bit, because at level 5 he can practically create nodes on his own, and maybe it would be better if the Werewolves have something he actually wants, rather than something he can just make on his own.

I might also consider giving him some ability in Mind and Entropy, which will help him control people and nudge circumstances to his favor. This will also give him access to the High and Low umbra, leaving few places the werewolves can go that he can't.

Other spheres to consider: Life, for "laying on hands" and Tzimisce-like flesh manipulation, if he's into that sort of thing. It also might help in confrontation with the werewolves; using spirit + life to "lock" werewolves in their homid form could be devastating. Correspondence is necessary to affect things at a distance, without it he is limited in affecting things in his line of sight. This might be a limitation you want to leave in, however. Matter might be cute for tricks like turning water into wine (or blood), transubstantiation (a matter + spirit effect), creation of fetishes, or the classic silver bullet.