Yaaaay! More Divine!
Me thinks your mangastudio skills are very excellent!

this lineart is not bad.

if i were you I'd accent the hiatus (that the gap between panels in comics) more to get it more expressive.
you also use a lot of different tones, which makes it a bit confusing. perhaps you could work on making it a bit "simpler". i personally think it is a bit "too much".

Random stalker of ArtistHospital:

Great lineart you have here! I love how clean and fine you've done on these characters and the details like on the clothes accessories and (omg) the shadow sketchings. I haven't seen much of Slayers but I love how you did Xelloss most of all, he looks every bit awesome as devilish as he is.

Just saying right now that I am not a MangaStudio/tone user, so to me the tones you've chosen look all right to me and are fine with the picture. But the two main things I wanted to critique about revolve more around your composition (direction and emphasis), and your execution (character pose, and how you did your highlights and magic effects).

One important aspect of composition making is drawing with the intention of guiding the audience's eye. So your intention is to make your foreground toon (FT) more bolder, correct? Thickening the lines is one way to definitely help it pop out, but another is when you might have the characters in the bg (BTs) actually looking towards the FT's area. Right now, both BT1 and 2 are looking away and out the left side of the page, which inadvertently also draws the viewer's eyes away from the FT and out to the left. They don't have to be looking directly at her, just moving their pupils to the right would already help. Lina's eyes are a little bit too spaced out- she's on the verge of going cross eyed there so you might want to bring them a little closer-but her general view direction is okay, and I giggled at the butterfly bit.

Execution: you want this to look as professional as possible and I applaud you for your efforts- but where your lineart is top notch clean, tight and consistent, your highlights and magic look sloppy in comparison. A big example is Lina's hair right down at the bottom, the highlight doesn't follow her hair flow as nicely as Xelloss and the other fellow's, and simply looks like a scribbled blob. The same could be said about the FT on the highlights on her pants. Then there's the guys' own highlights; I noticed some of the lines look allright, but then there'd be these random shorter choppy lines (like on the guy with long hair) that don't make sense. My only suggestions for these is to brush up some more the subject of Lighting, and get some reference pictures (anime or real life) on how (for example) Lina's highlights are done.

In terms of movement, I think the FT looks pretty lively to me with the curve of the entire body, the cross bend of her right arm and left leg and the flow of her hair. It all looks great but what's bothering me is what exactly is she doing? My first impression was that she was bracing against a strong wind as she is running towards the viewer because of her fist to her head, her back bent like that, and her pelvic, feet and legs generally facing us (nice torso to hip twist, btw). Upon closer inspection, my next impression is that she's casting magic. I couldn't read that at the get go because the magic lighting arcs were too thin and scribbly, and the white halo around the characters only hid those magic effects more.

To make the magic stand out more- take the stipling/splatterydotty background and just go right up to the edge of the characters. From what I can tell you can do a gradient with it because at the upper right I see that area a little darker (also fix the random solid black blob on the lower right, better to fill that with the spotty gradiant). I think it's fine to take away the halos because with the dude with the long hair, his solid black hair should keep him from blending with the spotty background, and as for the foreground toon her solid light tones against the dark spotty bg would only help pop her out more. I'm only guessing but since her magic emanates from her fists, those should be the only areas you can have a little white halo and then for the magic lightnings they have to be a lot thicker, and sharper (you have the flow of it down you just need to be more deliberate and intentional).

Sorry for the wall of text, but I am hoping this might help you improve on your cover, as it is a pretty dynamic looking one with so much careful attention to detail (apart from clothes-those knuckles on that FT's right hand and muscle!) all it really needs is more polishing.