So I recently had this beer and really loved it and would like to make something similar. I tried emailing the brewer and all the info I got was that it is heavily spiced and fermented about 10 degrees warmer than their other beers. I've never had a black saison before so it's hard to compare.
from their website (http://newhollandbrew.com/blog/beer-news/four-witches-black-saison/):
15° Plato, Alc. 7.3% by Vol.
"The Four Witches art, illustrated by Kyle Bice, develops on Golden Caps theme, with a nod to Wizard of Oz, as L. Frank Baum wrote the book while summering in Holland, MI. White and dark roasted wheat provide deceptively delicious body, and a playful reference to Ozs contrast between good and wicked witches. Caramel rye and barley continue the story, along with a unique yeast character and mild spicing."