Susan's mind instantly went back to the time she spent camping with her Uncle who was her Mother's brother and also a Muggle. Fire needed two things, fuel and oxygen. They were taking care of the fuel problem now, but how to take care of the air.
"We need to smother it," she said coughing, "but with something that won't just catch fire."
With out another thought she conjured a heavy blanket and cast a fireproof charm on it. It had been taught to everyone in Hufflepuff around the time of the first task. Then she drenched it with water and levitated onto the edge of the fire. There was another sizzle but the flames didn't seem to spring up so it must have worked. Susan coughed again the smoke was getting to her.