someone who claims to communicate with the dead in order to discover what is going to happen in the future, or who is involved in black magic (= magic used for bad purposes)

Leonardo da Vinci was thought to be a necromancer due to his extensive knowledge of human anatomy and his study of dead bodies. 列奥纳多·达·芬奇因为对人体解剖知之甚多而且还研究过死尸，所以曾被人当成是招魂巫师。

Necromancers were familiar with the spirits. 招魂占卜师熟悉涉及到灵魂的事情。