Complex sentence: Ježibaba tells Rusalka that, if she becomes human, she will lose the power of speech and immortality; moreover, if she does not find love with the Prince, he will die and she will be eternally damned.
Split into simpler sentences: Ježibaba tells Rusalka that, if she becomes human, she will lose the power of speech and immortality. Moreover that, if she doesn't find love with the Prince, he will die and she will be eternally damned.