One who gives of his offspring to Molech is not liable to stoning unless he hands the child over to Molech and passes him through the fire. The child would remain alive, being either passed between two walls of fire, or the parent would jump with him over a fiery pit. There were other forms of worship, though, where the child was actually burned.
A practitioner of Ov is a necromancer - one who communicates with the dead – by raising the spirit of the deceased from the ground and causing it to take up residence under his armpits, from where its voice emanates. A practitioner of Yidoni takes a bone of the animal known as Yadua and places it in his mouth, from where a voice then emanates. These are both liable to stoning, and one who inquires of them violates a negative commandment.
Art: Aleksei Ivanovich Korzukhin - The Wake at the Cemetery