Necromancy

Necromancy is the ability to summon the spirits of the dead through magical means.

Empath: The Luckiest Smurf stories
In the EMPATH: The Luckiest Smurf stories, necromancy is considered a forbidden subject at the Sorcerer's Guild and thus is not taught to any students. Papa Smurf himself refuses to engage in necromancy as he was taught that such ability could only be used for evil purposes and that "the spirits of the dead" could actually be evil spirits posing as the deceased.