Which kind of spells work best?

No spells work, magic isn't real.

Deuteronomy 18:10-12

10 Let no one be found among you who sacrifices their son or daughter in the fire, who practices divination or sorcery, interprets omens, engages in witchcraft, 11 or casts spells, or who is a medium or spiritist or who consults the dead. 12 Anyone who does these things is detestable to the Lord; because of these same detestable practices, the Lord your God will drive out those nations before you.