I which book were the Nightsisters first introduced. I remember The Courtship of Princess Leia by Dave Wolverton.
That looks like an artists interpretation of them and not necessarily the best but it is better than the standard witches crossed with vampires motif,lol.
Its like asian, crossed with native american meets the joker from the dark knight,lol.
Or maybe they are just some wacky KISS fans who did some serious drugs.