Marvel, comiXology Buy One Get One Free Until Feb. 23: Captain America, Uncanny X-Men, Black Widow, And More The BOGO offer from comiXology and Marvel is valid only at the Marvel Digital Comic Store or comiXology. The digital comics sale begins at 10 a.m. EST on Friday, Feb. 20, and ends at 11:59 p.m. EST on Monday, Feb. 23. by Anu Passary