Complex sentence: Mother Nature speaks to the Dwarfelles holding Thunderella accountable for not mastering her powers and accuses the other Dwarfelles of misusing the powers that she gave them and are supposed to work together to help Mother Nature.
Split into simpler sentences: Mother Nature speaks to the Dwarfelles and holds Thunderella accountable for not mastering her powers. She says that they are supposed to work together to help Mother Nature.