Complex sentence: The antagonists are the twelve Titans and the primordial god Pontos, a group of ancient gods who escaped from Tartarus, where they had been confined since the mythological era, and who seek to overthrow the Olympian Gods and regain control of the Earth.
Split into simpler sentences: The antagonists are the twelve Titans and the primordial god Pontos, a group of ancient gods who escaped from Tartarus, where they had been confined since the mythological era. They seek to overthrow the Olympian Gods and regain control of the Earth.