Necromancers are known to be able to heal.. it\'s just not all games that give them these abilities.. in D&D some healing spells are under the school of necromancy, in D&D is also the term \"white\" and \"black\" necromancy, healing goes under the white, whilst undeath/death and negative plane energy goes under black..
Mages that \"play\" with death also often end up as the most powerful in games like D&D, transforming themselves into liches.. you might call them demented, but their power far outgrows any other mages, and power is a major \"fun factor\", especially in rpg\'s..