OOoooo~ What's her element? Ink? That be cool! Like if there were ink creatures what splat black ink over everything(kinda like spilling paint over a beautiful picture) or eraser creatures, that would be epic!
You could have her be the typical, seductive, semi-classy, evil female bad guy, but have her represent cliches, which are often a result of art block, so that would fit with the whole idea of them fighting off art block.
What if she's just a spaz? She looks all hot, but is kind of a weirdo, like hot moms in anime. I can picture her charging up a powerful attack, there's a flash of light, and all of a sudden she's behind you giving a wet willy. Like Sheogorath, always finding something to do, wether its taking over the world or being strange and distracting. The personification of internet distraction and the reason a great idea in your head comes out looking like a bunch of scribbles.
I can see her personality being completely at odds with her appearance. She has Teh Sexy, but hasn't the faintest clue what to do with it—her interests lie in other directions. Of course, when someone reacts to her attractiveness, she might try to play off that if its to her advantage, but she does a poor job of it—almost to the point of it being a weakness.
Maybe she's a lazy person? Or is trying to make others feel useless because she gave up ages ago and became corrupted, something bad happened and she basically became a boring adult, who thinks 'Creativity is for kids', maybe a kind of office lady who is making others lose their creativity by giving them mundane and boring tasks? Thus some people consider her a good 'manager' who's always doing the job right by persuading her minions to be un-creative and only doing their tasks?
Oh man... She looks so amazing and sinister. Almost corrupt. Like she may have been normal at one point but turned after an event. And I just can't get enough of her design. It reminds me of an ink blot or black watercolor. As for her personality I have no doubt that you will come up with something that will fit her look to a T. Anybody who looks at your gallery for a few seconds can see that you have a latent talent for character creation. (Heh, latent talent. I made an unintentional anagram.) In any case this idea quite simply gets better with each drawing you do and if there is anything I can do to help or support you just let me know. Keep up the excellent work.
I want to say a master he could be a master of the sculpting or clay arts. Rather than be seductive she's manipulative through sure wit, able to mold ones thoughts to fit her needs. If she were to have that kind of nature I'd say her personality would be calm and collective, always taking in information and learning from a loose.
With a nature like that I'd picture her using it to reach the top of a social status in the creative arts using a fake persona while her real one uses the connections gained for whatever evil plot. Maybe something like steal the worlds greatest arts which would grant her some kind of power or something.
Maybe she's the queen of the Art Block monsters. She can be a master of acting too, make people feel like she's a nice sweet person, basically fooling people into thinking she's the total opposite of what she actually is. Then she lures them over to her place where she goes on to suck every last bit of creativity out of them either turning them into Art Block monsters or a husk of their former selves. To lure them into her house she first gains their trust or affection either through friendship or romance. She uses anything she can to get people.
Sorry I'm a writer so things like this come fairly easy to me.
I don't know if you have thought of a motivation or powers yet, but I was thinking maybe she really sucks at drawing. Like whenever she attempts to draw something it turns out a giant mess, very skewed and twisted. The kind of creation that you would think of when you hear the word "wretched" and then those messed up drawings could be the monsters the heroes have to fight. This could also be very funny if you paired her with an incredibly OCD personality. Anyway, just thinking aloud
how about...she TRIES to be that typical semi-classy, seductive villain but doesn't really get it most of the time? like, she mispronounces words, is absolutely horrible at death-traps (thinks far too complicated?) and goes at "seductive" with all the subtlety of a jackhammer - posing horribly obvious, trying to walk with so much hip swing that it affects her speaking etc. also bad at "typical" villain things? seductively trying to smoke a cigarette and getting a caughing fit, stroking a pet cat but finding out she's allergic. (just throwing out ideas) and she frequently falls out of her role when she's taken by surprise. like when an underling announces the heroes have taken a different route than what she'd planned, she falls into a horrible slang and stomps around with about the gracefulness of godzilla