Firestorm, the Nuclear Man, Vol. 1 #5 (1978)

Again: Multiplex!
The Hyena leaps upon Firestorm delivering a massive flurry of blows. The hero attempts to use his atomic restructuring powers to stop the Hyena's assault, but she moves too quickly for him to erect a defense. Hyena specializes in close-quarter combat and rakes Firestorm across the face with her diamond-tipped vibro-claws. Ronnie manages to animate a nearby electrical tower. The tower falls on top of the Hyena rendering her unconscious. Meanwhile at the Downtown Medical Center, Multiplex comes out of his coma. During his convalescence, he has learned more about his fission powers and now uses them to escape. Multiplex absorbs all of the electricity from the medical center and becomes a physical powerhouse. He breaks through the hospital wall and runs off in search of even more power. 
Release Date: 1978