If you look at a Wikipedia article with a banner that's functionally not unlike yours (this article needs improving)If you look at a Wikipedia article with a banner that's functionally not unlike yours (this article needs improving), you'll see there are a number of design differences. Namely:
- The banner is part of the article, placed directly under the article's title
- The banner is not as wide as the article, it's centered but slightly smaller than the article text.
- It has neutral colors, matching the rest of the page, but there's a contrasting icon drawing attention to it.
- The text in the banner is non-standard, with bold and italic parts and various blue links.
All of this makes the banner hard to miss and easy to parse. If you open the page you'll notice it immediately and it's easy to guess what it's trying to tell you.
Applying this to your banner, I'd create a padding area between the banner's edges and the article's edges. Right now it looks like a taskbar, window-menubar or ad-banner, something to ignore unless you're looking for it. I'd ditch the contrasting background color, opting for a single icon with text on a plain background to communicate its intent. If you feel like with these changes the banner doesn't draw enough attention you can try to change its position, play around with that, and perhaps change the text formatting. You can add a link to a page with a more complete explanation and perhaps make homebrew page and d&d wiki bold.
Alternatively, if you're brave enough, you could try altering the article's font. I think for something like a D&D wiki you could get away with a handwriting style font (one that's still legible) for user-made articles. It clearly distinguishes the user articles from the official ones and because of the formal/informal clash it might convey the intent that way. It would then become more like a user's 'notes' on a subject, instead of an article.
