Firestorm: The Nuclear Man #25

Mr. Freeze uses Firestorm to help get Killer Frost to the sun, where she proceeds to absorb the sun's heat. Being near the sun causes Firestorm's powers to go slightly haywire, but allows Professor Stein to access the matrix to give Jason advise. Firestorm defeats Killer Frost and returns to Earth where Batman has already defeated Mr. Freeze.