Story

Although Queen Zeal isn't the final boss, she is definitely one of the most important characters in the game. The following is a summary of her role:

When Crono and company stumble across 12,000 BC, they find themselves in a land filled with magic, ruled by a power-hungry queen. They soon learn that this queen, Queen Zeal, is using Lavos in order to obtain these magical powers and in order to increase her personal power. They then set out to stop the queen.

They follow her to the Ocean Palace, and once they reach her, she uses the mammon machine to summon Lavos, thus killing Crono. Schala is merged with Lavos, and Janus is sent into the future -- 600 AD.

At this point, the Black Omen is created. Queen Zeal refuses to let anyone destroy her eternal life, and Crono and company finally destroy both her and the mammon machine here. The only thing left to do after killing her is to kill the true source of evil -- Lavos.