Kiltering Mayhem - Chapter 62 - : Start Of The Celebration.

She was the Empire’s top-tier elite agent, skilled in both medicine and poison. One day, she transmigrated into the body of a foolish, mentally disabled, and hideously ugly waste. But when her soul entered, the Phoenix Maiden returned, shaking the heavens and the earth! Those who wronged her will be repaid a hundredfold. Those who insulted her will pay back a thousandfold. Call her useless? Wait and see what true genius in cultivation looks like. Call her a fool? Wait and see who the top-tier alchemist really is. Say no one wants her? Watch as the strongest man follows her everywhere. From now on, divine beasts and handsome men will walk by her side, and she’ll roam the heavens and earth as she pleases.‘Qingcheng, from now on, I’ll help you manage the household and raise our children. This world and I will belong to you!’ said the scheming man with a flattering smile.The woman coldly met his gaze and replied, ‘The world and its empire are within my grasp. Now, get lost!’

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

After a one-night stand, she faked her death and transformed into his flash-married ugly wife, while he didn't know that she was the woman from that night.Is the ugly wife really so unfashionable and greedy for food and lust? It's all an act. She's only trying to hide her real identity.They survived in the cracks of various schemes. When her hidden identities were exposed, the man's eyes were filled with coldness: “You pretended to be ugly and dumb, are you kidding me?”She smiled faintly: “Didn't you get any joy and pleasure from it?”He frowned: “You deceived me for my looks!”She held her forehead: “I can only blame you for being so good-looking!”He looked as if he wanted to swallow her whole: “I'm not someone to mess with.”She responded calmly: “It's getting late. Time to wash up and go to bed!”