Thank you for the tip!
I thought that she could maybe conjure demons or something like that so a monster on her head doesn't really sound like a bad idea to me. But yeah, I thought that it was obvious that it's a hat, but from an outsider's perspective, it isn't really that clear huh.
While we're at it, could I ask for your opinion on the color scheme? I'm not sure whether I should go with a more monochrome style (like #3) or something with more neon colors (sort of like the purple in #2).