Hyperborea by Clark Ashton Smith

A cycle of tales set on a vanished, primeval northern continent where decadent city-states, sorcerers, and monstrous gods enact strange rites and uncanny adventures; the stories use lush, baroque prose to evoke alien landscapes, bizarre creatures, and doomed passions, blending sword-and-sorcery action with cosmic horror and a mournful sense of civilizations fading into night.