Have you seen card game anime, or anime in general? Or would like to write a crossover? All it would take is coming up with a general plot, setting, some fun characters and then seeing what you can create.
You'd have me as a reader. I'm really interested in how each fanfic writer brings something new to the DM fandom. And if you don't want to be a writer, what sort of things would you like to read in DM fanfiction?