Complex sentence: In an archipelago overseen by gods who represent and guard the elements that each come in the form of an "orb", when these protector's reign comes to a close every 500 years, new heirs must be chosen through election by vote.
Split into simpler sentences: In an archipelago overseen by gods who represent and regulate the elements, each element's likeness is reflected in the form of an orb, that every god's duty is to protect. When these protector's reign comes to a close every 500 years, new heirs must be chosen through election by vote.