Complex sentence: Thousands of years ago, Steppenwolf and his army of Parademons attempt to conquer and remake Earth through the combined energies of the Mother Boxes before they are foiled by a unified army that included the Olympian Gods, Amazons, Atlanteans, ancient humans, and Green Lanterns.
Split into simpler sentences: Thousands of years ago, Steppenwolf and his army of Parademons attempt to conquer and remake Earth through the combined energies of the Mother Boxes. They are foiled by a unified army that included the Olympian Gods, Amazons, Atlanteans, ancient humans, and Green Lanterns.