Here's a couple of female versions as well, a bit more painterly to get a better feel for the whole character.
I added a necklace from the dogtags of her fallen team that's going to be a rather omnipresent element between versions.
Between the male and female options, I'm gravitating more towards the female for now. I just like the thinner sillhouette and believe a 'rapier' feel for the character would fit more with the physical shadows theme. The helmet from A grew on me, yet I'm kinda torn between B and D at the moment as a final(-ish) choice.

Art War 3 Sketches_2 Female exploration.jpg4018x1768 1.65 MB

I'd most likely go with the last version (D) as a base for the more ragged look (and who doesn't like a good coated villain :D)

Thanks Looking at them again, I agree with B being better...I might just push both B and D a step further and then decide, B does seem to have a more appealing design and recognizable form

Thank you, while 6 on its own is too alien imo, the more fluid feel is something I'll try to capture in the character (and yeah, it's going to be female for sure, the more I imagine the illustration, the more I dig the female ones)

So here's the more refined design for female B, I like how she's starting to look.
I decided to go for an unstable smoke rapier as her main weapon and added some faint smoke wings so she can gracefully float towards her prey.
As for the visual effects I'm gonna go for, I'm thinking of something reminiscent of volcanic lightning and smoke.
Due to her past as a soldier, she knows not to count completely on technology or magic, thus she carries a trusty gun on her as well.

Art War 3 Sketches_3 Refining Character design.jpg2378x2644 2.08 MB

I'm still not sure, however, on the amount of horns appropriate for her and whether I want her to have a hood or not

Next up - Illustration time

To begin with - thanks for the kind words @rgdraw and @Bruck

(Insert smooth transition) Illustration sketches:

Art War 3 Sketches_4 Illustration thumbnails.jpg2648x2281 2.23 MB

Some thoughts:
My personal favorites are 1 and 4 (which are almost the same thing anyway, so I'll combine them ;D). I like the tighter composition and feeling of grandeur in 1 and the action and wings in 4, so I'll be trying to fit the dangling guy in 1 so that he doesn't obstruct the main character.

2 feels a bit generic and lackluster (too much empty space).
3 is a backview of 4 and I don't think the back would showcase the character too much (even though it's a bit more ominous).
I tried a couple of more crouching poses (as if she's lunging or screeching at enemies), yet it didn't resonate too well with the whole elongated sillhouette I'm going for so those were completely scrapped.

Here's the rough 'victim placement' exploration. I'm also thinking about breaking the symmetry of the character a bit by removing/changing one of the pauldrons and possibly giving her a mech/shadowy arm (nothing too crazy) but that's yet to be tested.

As for the sketches at hand - I'm leaning towards 3, but opinions are welcome

Art War 3 Sketches_5 Illustration 1 Exploration.jpg2160x2903 2.49 MB