The X-Men #79

In "We Must Destroy...the Cobalt Man!", the X-Men take a rare break from their duties—only to be thrown back into action when a former Stark employee, now clad in a dangerous new suit, goes rogue. Written by Roy Thomas and illustrated by Werner Roth with inks by John Tartaglione, this 1972 classic sees the team racing to stop the unstable Cobalt Man before his suit triggers a catastrophic meltdown. The cover, by Gil Kane and Frank Giacoia, captures the high-stakes tension of the moment.