Described by de Camp in his introduction to the story as 'one of the most horrible' of Smith's tales, it chronicles the life and death of the dread sorcerer Namirrha.

According to Emperor of Dreams: A Clark Ashton Smith Bibliography (1978) by Donald Sidney-Fryer, "The Dark Eidolon" was first published in the January 1935 issue of Weird Tales.

Trampled almost to death by the horses of Prince Zotulla, he leaves the city and becomes a willing pupil of a wizard, driving his own bond with Thasaidon, Lord of the Seven Hells and God of Earthly Evil.

Soon, demon musicians and singers play, followed by gigantic horrifying dancers who crush all of the guests (who have been magically tied to the floor by a crimson fog).

Obexah, screaming on the altar, laughs insanely, while the macrocosmic stallions of Thamagorgos return through the skies to crush the palace of Namirrha.

Reviewing Out of Space and Time in the 1983 book The Guide to Supernatural Fiction, E. F. Bleiler remarked "The Dark Eidolon" and "The Weird of Avoosl Wuthoqquan" are "the best stories.