Dissia has a long, full, Witch dress. Like a ball gown for a Witch.
You can also download the hats. Witch hat patterns. Arcane Illussions – Witch Hat.
A bat dress, and garters, a bikini top and bottom which I haven’t linked to. It’s leaning more towards Halloween than Witch for me.
I do like the Moon Girl Swimsuit with the moon phases around the waist.