There were a few books that introduced the plot of immortals, Buddhas, and ghosts. They were the Primordial Ghost Lord, the Legend of Qing Kuang, the Sword of the River Styx of the Untainted Land, and the Inheritance of Grand Preceptor Wen. These novels belonged to the fantasy or xianxia genre. They involved all kinds of supernatural existences such as immortals, buddhas, gods, ghosts, demons, and so on. The plot was rich and colorful, and it was very worth reading. I hope you like my recommendation.