The book,"Wear It Quickly: The Paranoid Villain's Babbling in My Arms," fits the requirements, so I recommend this novel to you. The novel described how Nan Xiao, the leader of the heresy, was struck by lightning and transmigrated to various planes, becoming a villain. However, in each plane, there would be a special person who changed him. The novel was a fantasy romance, a supernatural ability, and matched the two elements of transmigration and the killing of the leader of the martial arts world. I hope you like this recommendation. Muah ~😗