Amethyst Oath

Different world + super power + practice "On the day I was promoted to the second level, I saw a chessboard in the sky that enveloped the entire world. I stared at it for a long time." "It moved! White had an extra piece. At that moment, under the moonlight, in the sky that even a single piece might not be able to touch, I got scared!" "It can actually decide my fate!" "I am a black man, and there will be a fight to the death within 20 moves."