I’m not even sure where I saw the ads but they mostly featured the eye catching covers that they did for the book.
The comic first caught my eye sometime in 1984 because of the stylish Dean Motter and Paul Rivoche ads that ran in support of the book. However a variety of creators have worked on the comic over the years lead by Dean Motter who is credited as Mister X’s creator. One of my favorite comic books from the 1980s is “Mister X.” It was originally published by Vortex Comics and, I think, they still own the copyright on the comic.