Chamber of Darkness was retitled Monsters on the Prowl with issue #9 (Feb. 1971), this version ran one new story each issue through #13 (Oct. 1971) with the remaining content consisting of reprints from Atlas Comics, Marvel’s 1950s predecessor, and “pre-superhero Marvel”, primarily drawn by Jack Kirby or Steve Ditko. It expanded into a double-sized, 25-cent comic for two issues (#13-14, Oct.-Dec. 1971). Some issues of the reprint books featured new covers by John Severin, Marie Severin, Gil Kane, and Herb Trimpe.
EHT Comics 