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I found this Brian Bolland cover to the 1982 London Editions Magazines collection of the the Warworld story at the Gad, Sir! Comics! blog. This British hardcover reprints DC Comics Presents #27-29 and some random Superboy story. This was Bolland's second depiction of Mongul, after his cover art for DC Comics Presents #43. Also featured are Superman, Supergirl, the Spectre and likely Bolland's first shot at Martian Manhunter. Ain't it grand?