Use your Earth breath to knock her health bar down. YOnce you knock her back to the orange health bar she will start flying around and breating fire around the island. After a few laps she lands again- hit her with earth Breath when this happens. Once the orange bar is taken care of you get a new breath ability, Convexity Breath. This will whittle her last health bar down to nothing fairly quickly- once you have done that get closer to her and let loose the Fury attack. This will trigger the final cutscenes.