Complex sentence: The series portrays Avatars as human-like beings with supernatural powers who embody good and evil, whose constant and age-long struggle should serve as an explanation for Dark Ages or Ages of Enlightenment throughout mankind's history in the real world.
Split into simpler sentences: The series portrays Avatars as human-like beings with supernatural powers who embody good and evil. Their constant and age-long struggle should serve as an explanation for Dark Ages or Ages of Enlightenment throughout mankind's history in the real world.