Muzan Kibutsuji in the manga is presented as a truly evil force. He has a commanding presence and his actions drive the plot forward with a lot of intensity. His character design and personality traits make him a memorable antagonist.
They could interact in a very confrontational way. Michael Jackson, with his kind heart, would likely be appalled by Muzan's evil deeds. He might use his music as a weapon to try and drive Muzan away or at least make him see the error of his ways.
Muzan was ultimately defeated by the collective efforts of Tanjiro, Nezuko, and the other demon slayers. Their teamwork and perseverance were key to ending Muzan's reign of terror in the manga.
Prometheus' death in the comic is quite a significant moment. It might come from a battle with a powerful villain or due to a twist in the storyline that leads to his downfall.
Well, Geralt might die as a result of a powerful curse or magic. Maybe he angered a powerful sorcerer or witch who cast a spell on him that he couldn't resist. This could be a slow and agonizing death as the magic takes its toll on his body and mind. Another possibility is that he sacrifices himself for someone he loves or to save the world from a great evil. He might put himself in harm's way knowingly, and in the process, lose his life.
Superman's death in comics is often a result of epic battles or selfless acts. For instance, he might face an opponent whose power is just too overwhelming, or he might give his life to prevent a major catastrophe.