Complex sentence: They are magical ladies who guard castles, caves, bridges, wells, rivers, and treasures, and they can promise treasures to those who break their spell or to those who keep secrecy of their gold.
Split into simpler sentences: They are magical ladies that guard castles, caves, bridges, wells, rivers, they are also guardians of treasures. They can promise treasures to who breaks their spell or to who keeps secrecy of their gold.