Complex sentence: This reality is set 50 years in the future after many of the costumed villains and criminals joined forces to kill most of the various costumed heroes, and subsequently conquer the United States.
Split into simpler sentences: This reality is set 50 years in the future after many of the costumed villains and criminals joined forces. The result is the death of most of the various costumed heroes and the conquest of the United States.