Complex sentence: He later becomes the leader of the Hellfire Club, a secret society bent on taking over the world and starting the next World War, which is stopped by the first X-Men during the Cuban Missile Crisis in 1962.
Split into simpler sentences: He later becomes the leader of the Hellfire Club, a secret society bent on taking over the world and starting the next World War. This plot is stopped by the first X-Men during the Cuban Missile Crisis in 1962.