Complex sentence: She finally uses her shapeshifting skill to transform into a gigantic green serpent, but the Prince recognizes her serpent form as the same one that killed his mother ten years earlier, and after a brief struggle, he strikes off her head.
Split into simpler sentences: She finally uses her shapeshifting skill to transform into a gigantic green serpent. But the Prince recognizes her serpent form as the same one that killed his mother ten years earlier, and after a brief struggle, he strikes off her head.