You have inherited the Demon King's strongest technique, The Ruler. This technique allows you to "invert" all attacks and effects of powers used against you. Any attack against you will no longer harm you, instead it will heal you, while any attack meant to weaken you will instead strengthen you. However, as it works on the concept of magic inversion, it is not without it's own drawback, as any magic meant to strengthen you or increase your power will instead weaken you, while any magic meant to heal you will damage you instead. You can easily overcome this weaknesses by deactivating your power.