Ok let me clear things up that I looked over.
The Corrupted Wizard is a neutral role. He kills anyone he pleases.
You CAN vote for yourself, but why?
Mafia wins if there are less townies then there are mafia members. HOWEVER they can't win if the Corrupted Wizard is alive at the end.
Townies win if the Mafia AND Corrupted Wizard are voted out.
The Corrupted Wizard wins if he is alive when the Mafia wins.
So the Corrupted Wizard(CW) is a Mafia member because his only win condition is for the Mafia to Win and CW to be alive but, the Mafia Can't Win because the CW is alive. Therefore the CW can't win unless their are 3-4 players left (2 Townie, 1 Mafia, CW) and the Townie vote out the Mafia, Mafia Hits a Townie, and the CW kills a Townie. Effectively making the CW the only person standing and winning by virtual of everyone else being dead.
Hogwarts - Mafia = Townies Win
(Mafia > Townies) && !CW = Mafia Win
!(Mafia || Townies) = CW Win
Everyone has to be dead first for the CW to win. CW Literally has to destroy all of Hogwarts to pull a win.