Complex sentence: After reclaiming the helmet, he is greeted by Raiden, who is revealed to be his grandfather, the Moon King, who wants to take Kubo's other eye in order to join his "family" and make him immortal like him.
Split into simpler sentences: After reclaiming the helmet, he is greeted by Raiden, who is revealed to be his grandfathe, the Moon King. He wants to take Kubo's other eye in order to join his "family" and make him immortal like him.