It´s a good idea to have an apprentice, especially an ambitious one who is willing to get his hands dirty. Your apprentice will be of great assistance for many tasks. fx:
Digging up corpses, exploring dungeons... going in first.. Serving as a meat shield in combat, Gathering ingredients for your dark magic, simple sacrifice in a perilous situation etc. It is important to find the right apprentice, one whose skills fit your plan for dominion. Don´t choose a digger-type, if your goal is to fly around on a skeletal dragon and explore dungeons, then you should rather choose an eager scythe slinger, who want´s to prove his courage and fighting skills. Be sure to teach your apprentice enough to make him become usefull. If he isn´t usefull, well, send him on a mission, that you know he will not come back from. After all, there will most often be a new apprentice waiting to take his place. Rule number one is that your apprentice is always expendable.