Heartless
Heartless magic is the process of possessing others for their own gain. There are many names for the practitioners who use this form of magic; Liches, Hags, Parasites, etc.
Methodology
Heartless is a immaterial and price oriented school. Every use gradually pushes the practitioner away from humanity and closer to becoming Other. However it is an excellent way to quickly regain power, youth, and other abilities. They tend to focus on the long term. Often preferring to stick to small, subtle effects, and then constantly layering it for reinforcement.