This class would be totally based off of your pets. Pure DPS class. You personally do not cast anything offensive. Any spells you get are all directed to the pets and either causing them to do more damage or give them special abilities or .....you name it.
I envision a small army of pets doing you bidding.
While we do have pet classes currently none of those classes are totally based on the pet being the primary damage dealer. I guess that is what would make the necro or Lich different and special.
The necro/Lich should have auras or stances like Dk's.
if you chose the necro spec all your pets will be some form of undead that rise to your bidding. if you chose the Lich all the pets will be demonic. Make them new classes of damage. Necro damage and demonic damage. Each bringing their own different benefit.
Anyhow this is just a thought and by no means complete.
I really like it because this class would be DARK...I personally think WoW has turned too much into a foo foo lets kill bunnies game and needs to take a turn for the dark/Evil side. This class would help usher the new era in.
What you all think. Feel free to add ideas.