It's finally time to confront Lavos.
After an excruciatingly long journey through the Black Omen, battling monstrous creatures, the party faces Queen Zeal. When Zeal is pretty much defeated, she throws them into the Mammon Machine where they battle this Machine in a whole other dimension.
When they defeat the Mammon Machine, the party then has to fight Zeal once again. All that's present is a magical image of her face and hands. After Zeal is finally defeated once and for all, Lavos appears...which leads the party into the final battle.