The Tale of Satampra Zeiros

They are short on money, so Zeiros suggests they plunder Commorium, the abandoned former capital city of Hyperborea.

The liquid rises out of the basin and shapes itself into a monster with an enormous head, tentacles, and a dozen legs.

"Satampra Zeiros" is a story written in the style of Lord Dunsany, who wrote a similar tale of thievery gone wrong called "How Nuth Would Have Practiced His Art upon the Gnoles".

Robert M. Price points to Dunsany's "Bethmoora", featuring another deserted city, as an additional likely inspiration.

[2] When Smith sent his friend H. P. Lovecraft a copy of the unpublished manuscript, he responded with "well-nigh delirious delight.... You have achieved in its fullest glamour the exact Dunsanian touch which I find it almost impossible to duplicate....