I made about 3 different brow furrow HD morphs in Zbrush months ago. This is probably best of the lot, 1 level subdivision in creation, increased to 2 here. Took some digging to find this hidden in one of my dozens of LF morph scene files... it's not perfect but it's good enough. Furrowed brows are tough without the right topology conducive to it. I imagine if you crank up the subdivision better results can be had but by rote I keep my HD morphs at one or 2 levels. La Femme loads at 1 level preview/2 render so I try to stay in that ball park... most of the things I do would only require 2 levels at most.