Action Comics #754

Stuart Immonen and José Marzán Jr. deliver a genuinely unsettling cover for "The Aimless Blade of Science" — a wide-eyed, horrified Superman is engulfed by a sea of floating skulls against a starless void, while above him looms a cold, blank-faced figure in a yellow-and-red costume radiating a fiery orange burst. The tagline "Nightmares Become Real… and Reality Is a Nightmare!" sets a mood that's more psychological horror than straightforward superhero fare, and it works beautifully. A compelling May 1999 chapter in the Superman saga that earns its place on any shelf.