40 years ago, 1984's Secret Wars changed Marvel Comics forever. Heroes and villains were torn from the Earth and thrown into a makeshift Battleworld. The Beyonder made a name for himself as a devastating cosmic threat, Doctor Doom rose as a premiere villain, and superheroes began revealing their true colors in the face of devastating circumstances.
Source：https://www.cbr.com/secret-wars-1984-marvel-best-event-comic/
