There is no credit for the cover art in the credits in the issue. DC Comics website credits the cover to W. Scott Forbes, but this appears to be incorrect. There are initials that appear to be a stylized JEF on the cover. These same initials appeared on the covers to issues #1-3 and #10, all of which were credited to Juan Ferreyra. Juan's twitter account @juanferreyra has a post dated 10/18/16 which features the art for this issue's cover, although in that post he refers to it as his cover for Green Arrow #15 (instead of #14).
Art credits in issue credit the art to Elenora Carlini, Carlos Rodriguez, and Gus Vazquez. It does not list separate pencils and ink credits, so assumption is made that each pencilled and inked a portion of the issue.