The villainous Deceidon and his minions, from the novel Urshurak (1979), by Greg and Tim Hildebrandt.
The Hildebrandts had enjoyed much success with the fantasy genre in the 1970s, with a series of calendars based on the works of J.R.R. Tolkien, and providing the illustrations for Terry Brooks' 1977 fantasy epic The Sword of Shannara. So it was understandable that they wanted to produce a work that was theirs alone.
They originally conceived Urshurak as a film, and shopped the concept around Hollywood. However, no studio would touch the project due to the cost; this was long before Peter Jackson's The Lord of the Rings trilogy became a box office juggernaut.
The brothers then took their storyboards, character sketches, and paintings and, joining with writer Jerry Nichols, produced a 400+ page fantasy novel.
Like Brooks' Shannara novel, Urshurak is highly derivative of LOTR. Unlike Brooks, though, Nichols is not a very good writer. Reading Urshurak was a slog, with dialogue that seemed lifted from the worst comic books, repetitive scenes and action, and cookie-cutter characters. The only good thing the book had going for it was the artwork from the Hildebrandts.