Marvel Two-In-One (1974 series) #21

In 1976, the Thing and Human Torch receive a visitor at the Baxter Building: Janice Lightner, asking them to stop her brother Tom Lightner, obsessed with recreating their late father Raymond’s experiments with a stellar cannon to draw the power of the heavens into a human body.

1936: Doc Savage and his aides receive a visitor at the Empire State Building: Lucinda Lightner, asking them to stop her husband Raymond Lightner, obsessed with using a stellar cannon to draw the power of the heavens into a human body.

In their respective eras, the mad astronomers fire the cannon, creating a rift in time, hurling all the heroes into one spot and fusing Raymond and Tom into a new super-powered being—Blacksun.

The heroes of two different decades recover quickly from their surprise and team up to battle the menace. Nothing seems able to stop Blacksun—until the massive energy stored in his body burns him out.

The temporal field fades, sending Doc and his men back to their own time, while Thing and the Torch rush Lightner to a doctor.