Necromancy

Necromancy was a school of Magic that explored the narrow divides between life, death and undeath. Necromancers manipulated life energy becoming able to sap it from the living and grant it to the dead or the undead or even use it to empower themselves. With further study necromancers could deny death in others or find ways to slow, prevent or make contact with the deceased to learn from the remnants of their being. 
Necromancy was considered taboo in most civilized societies who feared their desire to desecrate the bodies of the dead and of their ancestors. The pursuits ability co cause unnatural effects was also feared with the denial of death being considered an abnormality of existence in defiance of the will of the gods. Some societies did accept necromancy however such as in Solstein where it was practiced by Clan Død.