Read "Witch Dance" at The Eldritch Dark:
This poem from Clark Ashton Smith (CAS) first appeared in the September 1941 issue of Weird Tales magazine, which featured what has to be one of the best cover illustrations that Margaret Brundage ever created for that publication.
Given that The Unique Magazine was only published every other month in 1941, this would have effectively been the Halloween issue for that year, and "Witch Dance" fits the bill perfectly:
As in the Sabbat's ancient round
With strange and subtle steps you went;
And toward the heavens and toward the ground
Your steeple-shapen hat was bent
As in the Sabbat's ancient round.
The use of repeated words at the end of the first and last lines in each stanza is an unusual technique for CAS, used to best advantage in the second and seventh stanzas, where the first and last lines are repeated (almost) verbatim.
Although the subject of the poem is appropriately supernatural in anticipation of All Hallows' Eve, it's also quite an erotic work:
Your supple youth and loveliness
A glamor left upon the air:
Whether to curse, whether to bless,
You wrought a stronger magic there
With your lithe youth and loveliness.
CAS provides some background on the specific source of this poem in a letter to Samuel Loveman from 1941*, referring to the dancer (and friend of CAS) Madelynne Greene:
One or two pieces, such as Witch-Dance, have been suggested by Madelynne's dancing: she once did her Witches' Sabbat for me by firelight and moonlight here on the ridge, as described in the poem.
Taken all together, "Witch Dance" is a very seductive work, an amorous vision of a sorceress in the act of summoning.
*See letter #365 in Born Under Saturn: The Letters of Samuel Loveman and Clark Ashton Smith published by Hippocampus Press.