It's hard to say, Tbora. I have been trying to build something similar to be one of main behind the scenes evil NPC for the game I am going to be GMing. Yours looks like it works for your concept as well as anything I have come up with. There are a couple quirks that seem off to me, but that are probably essential for your build. One thing that strikes me about your build is that it has never taken refinement, which seems out of place considering everything else it has picked up. It seems odd that a character would have developed ghost speaker, marked by power, and picked-up more lawbreaker stunts but never try to improve their base magic. On the other hand, from a power-gaming perspective, I cannot do better than what you did if sheer offensive punch and casting him as a sorcerer and not a wizard does partially justify the lack of interest in acquiring more knowledge.
My version (which does not have to worry about negative refresh since it is by definition, an evil NPC) does not have the demonic pimp cane because I am leery of allowing lawbreakers inside an item of power (the Blackstaff seems to me to be almost one of a kind). To make up for it, I dropped marked by power (my evil wizard does not need this but you do), ghost speaker, (ditto) and reduced the lawbreaker stunts to -2 each (just like Grevane from OW: 155) and added 3 levels of refinement in order to turbocharge his necromancy and give him some defensive depth. I also wanted to give him some sort of defensive option since he almost has to have enemies (e.g. the White Council views him as kill on sight), hence the item slots. In the same vein, I gave him worldwalking instead of transformation to ensure that, with his Great Lore and Superb Discipline, he could open portals to the Nevernever in a hurry if he needed to escape with no prep (YS:283 base complexity is Superb so he can do it as is possible and save the fate point that your version would need to do it for a failed discipline role to open the portal in one exchange). My build is as follows (I did not change the skills):
High Concept: Kemmlerite Bastard of a Demon Lord
Trouble: Under My Father's Thumb
Skills:
Fantastic: Conviction, Discipline
Superb: Rapport, Endurance, Lore
Great: Deceit, Alertness, Contacts
Good: Resources, Intimidation, Athletics
Fair: Fists, Guns, Burglary
Average: Scholarship, Craftsmanship, Driving, Mights, Survival
Powers:
[-3] Evocation (Spirit Power +2, Spirit Control +1)
[-3] Thaumaturgy (Necromancy Control +2, Worldwalking Complexity +1)
[-2] Kemmlerian Necromancy
[-1] The Sight
[-0] Soulgaze
[-0] Wizards Constitution
[-3] Refinement (the added specialties listed above plus an extra focus item granting +1 Defensive Spirit Control and two enchanted item slots Granting block four or Armor:2 three times per session [2 enchanted item slots).
[+2] Demonic Pimp Cane
[-2] Law Breaker (Fifth Law)
[-2] Law Breaker (First Law)
[-1] Marked by power
Total Refresh: 1
My version can throw out 11 shifts of necromancy (13 if trying to kill). Yours can do 11/14 shifts but does not have the ability to do much of anything else whereas mine can also dish erect a Legendary shield using spirit for times when your zombies are not available. Your eggshell armed with a hammer version, by contrast is a better offensive threat, but cannot defend itself at all if surprised (it takes 2 exchanges to activate your version's necromantic defense).
P.S. Your version, because it has superb endurance, should have an extra mild physical consequence.
