Merchant of All Realms of Cause and Effect

Between heaven and earth, everything has a price. The protagonist inherits a mysterious shop that sells lifespan, talent, luck, magical weapons, magical powers, and even the future. "In one hundred years of life, you will become a saint once." "Future wife? For sale." "Supreme Bone? You can buy it back." All transactions have consequences. The more transactions there are, the stronger the path of cause and effect the protagonist controls. Finally, it was discovered that this shop turned out to be the back door left by Tiandao in the previous era.