Or a charmer, or a consulter with familiar spirits, or a wizard, or a necromancer.

Wesley's Notes

18:11 A charmer - One that charmeth serpents or other cattle. Or, a fortune - teller, that foretelleth the events of men's lives by the conjunctions of the stars. Spirits - Whom they call upon by certain words or rites. A wizard - Heb. a knowing man, who by any forbidden way's undertakes the revelation of secret things. A necromancer - One that calleth up and enquireth of the dead.

Matthew Henry's Concise Commentary

18:9-14 Was it possible that a people so blessed with Divine institutions, should ever be in any danger of making those their teachers whom God had made their captives? They were in danger; therefore, after many like cautions, they are charged not to do after the abominations of the nations of Canaan. All reckoning of lucky or unlucky days, all charms for diseases, all amulets or spells to prevent evil, fortune-telling, &c. are here forbidden. These are so wicked as to be a chief cause of the rooting out of the Canaanites. It is amazing to think that there should be any pretenders of this kind in such a land, and day of light, as we live in. They are mere impostors who blind and cheat their followers.