Hero Law is an absolute Magic that is capable of defeating anyone the user sees as foe, and can cancel out any kinetic or supernatural power (this also includes Saitama's supernatural abilities and Tatsumaki's telekinetic abilities). It is very possible Saitama could actually be defeated by this technique. This technique is also very possible to defeat Yugi despite her 900 trillion abilities. The magic was created by Mavis Winchester, one who first Heroes to join the Association, and is considered to be one of the most powerful S-Class heroes of all time.