Dask, that is the ad, and that's got to be the mag in which I saw the ad, since I know I used to have a copy. (What happened to it?) I wonder if this was the only time and place that Beagle (Ballantine) ran this ad?
Can everyone read what's at the bottom of the ad in small print? After all these years, I seem to have remembered it pretty well but not verbatim. It did appear on the inside of the front cover, right?
Thank you for sharing this bizarre and obscure bit of Lovecraftiana with us. (You have to love the "headline"!) I hope you had fun rooting it out!
I think there were only about three issues of Worlds of Fantasy (with that remarkably crude hand-lettered-looking title!). Maybe they'd have lasted longer if the mag had looked classier. I don't remember the content of the mag other than that complete-in-the-issue Earthsea novel and the Lovecraft ad. One might think it would have sold reasonably well...
Edit: I found this list of the mag's contents:
Contents include: What Do You Mean - Fantasy? by Theodore Sturgeon / In the Cards by Robert Bloch / Among the Grimoires by Lester del Rey / The Tombs of Atuan by Ursula K. LeGuin / If A Flower Could Eclipse by Michael Bishop / Me-To by Sonya Dorman / Death of a Peculiar Boar by Naomi Mitchinson / Santa Titicaca by Connie Willis (Constance Elaine Trimmer Willis) / A Ship Will Come by Robert F. Young / The Man Doors Said Hello To by James Tiptree, Jr. / Funny Place by Naomi J. Kahn.
That must be quite an early Connie Willis story. I'm not an expert on sf and fantasy -- not compared to some people here, anyway -- but I recognize all those names except Dorman's and Kahn's. It would seem, then, that this magazine had a pretty fair array of talent, to take this issue as representative, but it doesn't seem to have lasted long. Maybe it didn't have good distribution.