Superman #213

Superman #213 (On Sale: November 7, 1968) has a cover by Carmine Infantino and Neal Adams.

We begin with "The Most Dangerous Door in the World" by Cary Bates, Curt Swan and Jack Abel. Superman issues a statement to the public that a special vault with valuable contents will open when he dies. The vault is made of indestructible Supermanium and is kept under heavy guard. Luthor, provoked by articles in the Daily Planet, renews his efforts to kill the Man of Steel, who exhibits signs that he is weakened.

Luthor steals the vault uses a modified version of Brainiac's shrink ray. He then uses robots with Kryptonite inside to kill Superman. Thinking that he has finally succeeded in his goal, Luthor waits for the vault to open. When it doesn't, he uses every means necessary to break into the vault.

Luthor finally succeeds in opening the vault and discovers Superman inside. The Man of Steel apprehends Luthor, then explains that Mordru had magically imprisoned him in the vault. Supergirl and the adult Brainiac 5 then tricked Luthor into opening it by having the Legionnaire pose as the Man of Steel. Angry at being tricked, Luthor is nevertheless sent back to prison vowing vengeance. Reprinted in Best of DC #27.

The back up story is "The Orphans of Space," a reprint from Superman #144 by Jerry Siegel and Al Plastino. Superman, Supergirl, and Krypto are at the Fortress of Solitude when the Man of Steel notices a plane trying to land nearby. Superman uses the capes of the three heroes to make warning flags so the plane does not land and discover the Fortress. When the plane leaves Superman returns the capes and experiments with a machine he has found.

The machine causes a huge explosion that destroys Earth. The super-trio are the only survivors. Shortly, the Interstellar Council brings Superman up on charges for destroying the planet. All three are stripped of their powers and relocated to a primordial planet.

The three awaken to discover that it was a Red Kryptonite induced hallucination. Apparently their capes were exposed to a Red K mist while used as flags. Superman removes the dust and stores it in a lead container in the Fortress.

Edited by Mort Weisinger.