Action Comics (1938) #1078C

Two worlds in peril; only one can be saved. Teaming with his fellow Justice Leaguer, Mr. Terrific, to defend against Aethyr's deadly machinations, the Man of Steel is left on the defensive and out of options. Superman must choose which realm to save: Earth or the Phantom Zone! 

Plus, Supergirl falls under the spell of Koncept!