In 1977-78 I bought a sci-fi paperback, I remember titled "Planet of the Gworfs" (or perhaps "Planet of the Gwarfs")
The cover featured your standard, over-the-top 70's sci-fi cover painting with garish green colors, some kind of wolfman-looking creature and a large toad.
It may have been a compendium, but I recall it being a short novel, approx 200-250 pages.