This is Thrilling Wonder Stories for December 1950, and none of my usually reliable sources can tell me who painted this strange cover. The ISFDB entry for the issue is here. I found this version of the cover at Pulp Covers, where the curators also provide some nice interior art. There is this drawing by Paul Orban illustrating Leigh Brackett’s story “Citadel of the Lost Ages.”

And this by Vincent Napoli illustrating Frank Belknap Long, Jr.’s “If You Don’t Watch Out.”

You can download and read the entire issue from the Internet Archive.