From publisher blurb: Keep it Simple: Resistor Simple classes are trimmed-down, streamlined classes designed to be easy to pick up and play for both new players and system veterans! Each has a sleek core set of abilities that isn’t bogged down with options backed up with a strong but balanced chassis (HD, saves, BAB, etc). Resistor Base Class (Pathfinder 1st Edition) Resistors are, for some reason, all but immune to a specific type of magic. That limited immunity grows as they grow in power and eventually renders them resistant, if not totally immune, to all forms of magic.