I really like that idea! I also see that you have a great sense/taste of color scheme, as well as good dynamics in over character design! Very impressive.
Also, as much as I adore those giant gauntlets, if you really want to stick to succubus theme, I guess you should explore 1st variant more, by adding more design elements, like wings or maybe some more fancy dress elements, or maybe even some elements! As good as 2nd variant is, it gives me more of an imp vibe rather than succubus vibe. (But of course it all depends on whatever you like the most ^^)
This is my first Art War as well, despite that Art War is still a very young competition, so don't be too nervous, just be active on forum, leave a lot of feedback for other participants and you will find a lot of help here really fast! (Btw care to check out my first thumbnails, there are not much, still worth checking out!)
I will make sure to follow this post! So I will be waiting for more progress from you!
Keep it up, you are doing great!