Is a medium or a wizard: in 19.31 the prohibition is against seeking the advice of such a person, but this verse condemns the person who actually commits such practices.

They shall be stoned with stones: see verse 2. This passive construction may be rendered “you [plural] (or, someone) must kill them with stones,” or something similar.

Their blood shall be upon them: see verses 9, 11, and others.

Quoted with permission from Péter-Contesse, René and Ellington, John. A Handbook on Leviticus. (UBS Helps for Translators). New York: UBS, 1990. For this and other handbooks for translators see here .