Blacksmith vs. the System - Chapter 200

A skilled but unfortunate modern-day assassin was killed in a freak accident. However, he soon found himself summoned to another world by an evil wizard, who had him possess the body of a boy as an experiment. After successfully planning the evil wizard’s downfall, he used the wizard’s body as a springboard to gain influence and power in his new world.

- Description from Novelupdates

Drugged one night by her ex-boyfriend, a mysterious man took advantage of her in an ecstatic night filled with sex.To take her revenge, she married the man, and used him.

After Xia Feng transmigrated, his heart was mysteriously removed.In its place, a defective demon heart capable of sustaining life only for eighteen years was implanted.This is a magical heart that can sync with the power level of its target.To stay alive, he bound himself to the ultimate villain of the future, a Destructive Witch who was destined to destroy the world.The stronger the Destructive Witch becomes, the stronger he becomes!Thus, Xia Feng realized, it's not my fault for stirring up trouble: “Miss Witch, I admit you're strong, but not strong enough!”

An ineffable rebirth, taking advantage of a mystical magic cube that was produced from rebirthing to pass through various worlds(anime, novel, movie, games, etc), collecting whatever I want to obtain!

- Description from MTLNovel