My Self-Created Cultivation Technique: The Yin-Yang Grinding Disc

For some reason, a torrential downpour hits the modern world, causing the netherworld and its ghosts to spill into reality, opening rifts to other worlds, and creating spatial fissures between the realms of immortals, demons, and ghosts, as well as allowing extraterrestrial beings to appear. The rifts lead to an alien invasion. In one obscure little world among the three realms' three thousand minor worlds, an ordinary man from modern civilization appears. From the start, he is caught in a rainstorm while climbing a mountain and struck by lightning, awakening a cultivation technique he created himself: the Yin-Yang Grinding Disc. Gods, immortals, ghosts, and aliens are all trash.