Some time ago, based on some House Rules of my 2nd edition Warhammer campaing, I did some careers for the 3rd edition to allow my players to take the role of a wizard renegade or an experienced Warlock. Kind of covering the transition of a wizard to the dark side, until he dies in a pyre or he becomes a NPC chaos sorcerer. Similar to the doom fate of a Slayer, which you play knowing your only destiny is death.
Finally, these careers weren't of that much use, because I have a large party of players (8 to be precise) and there is always someone playing a Witch Hunter, a Priest of Sigmar, or similar, which makes the situation of the party unberable.
Now, with the arrival of Hero's Call, I have modified the career advance scheme, and despite what I said, I share the idea for those who may be interested. Sorry for the extremely boring and dull names of the careers.