From the waist up, one could be mistaken for picking the figure before them as being a Drow maiden of moderatley good looks. All the typical facial features are there, narrow face pointed at the chin, long pointy ears, silvery white hair, and sharpish nose. Even her torso and arms have the slim, toned look of her kin, with smooth, hairless skin, and a modest sized bust edging in the upper B-cup range.
It's once someone's gaze drifts to below the navel that her appearance takes on a monstrous change. From her waist down, her smooth skin morphs into hard chitchin. Instead of long, gracefull legs, one would see the body of a large spider. The bulbous abdoman as large as an ale keg, with eight spindly legs poking out from underneath.
If one was to study her face again, they would notice the dark, sadistic stare of her red eyes. And if those purple painted lips were to part in a grin, pointed fangs would be seen.