Leveling through Lust - Chapter 326

The dominant forensic doctor who traveled back in time to the era of the Great Tang's Zhenguan reign, became a distinguished family's abandoned girl.

After forming a blood pact with the Saint and Demon ladies, the good-for-nothing young boy obtained the Yin-Yang divine veins, learned the art of alchemy and martial arts, and dominated the world.The young Shen Xiang had a romantic encounter with a goddess and a witch, and obtained their supreme inheritance, acquired a divine vein that defied the heavens, learned peerless magical skills, and mastered superb alchemy techniques, which made him very successful on the road of martial arts... When he was hungry, he would refine some pills as snacks, when he was lonely, he would flirt with the high and mighty goddess, when he was bored, he would play with those martial arts masters who came to ask for pills, and when he was tired, he would let the delicate wives around him give him massages...

He is a young man without a spirit root. It is believed that this denies him the chance at cultivation. However, a mysterious lady imparts a Supreme Demon Classic to him and from then on, he starts his path of cultivation.
He undergoes a total transformation to emerge as the most fearsome and powerful fiendish demon in his era, that even immortals and fiends are fearful of him, and saints are at his beck and call.
Mastering the Supreme Demon Classic is the turning point in his life. He is able to unleash his immense and divine power from within, illuminating the entire universe!

- Description from Novelupdates

In her past life, Michelle was an ordinary doctor who worked in a small hospital, but once in a while, a strange envelope would arrive at her apartment and she would take up a weaon and turn into a deadly assassin known for her stealthiness. But being a top assassin, Michelle had many enemies and ended up dying, only to wake up in the body of Michelle Grace, a pampered young miss in a world similar to ancient dynasties, except that cultivation existed there. Not everyone could cultivate, but Michelle Grace could.The original Michelle Grace was engaged to the Crown Prince, and he killed her before Michelle took over the body, so after making a deal with Michelle Grace's father, the Archduke, Michelle took on the name Grace and started a revenge plan on the Crown Prince, his lover, his mistress and his father, the Emperor.A bit troublesome: Michelle gained the attention of two men who together were the Dark Lord. They were horrifyingly powerful, so Michelle had to be careful around them. Luckily, they didn't have in their plans harming her, as they were intrigued by her constitution. Michelle possessed a rare blood, which they could use.