No logos, no class icons
Doing fanart for sale is already illegal but let’s be honest, unless it’s for example Disney you shouldn’t worry.
But you should never use the game logos or company logos, and preferrably but not neccessarily avoid writting directly the name of the game (and companies involved, of course). The company may take action alleging that “it’s misleads people into thinking it’s an official product”
You can make your own closely-ressembles-but-not-quite variant of the game logo or the dragon on it if you really want to use it
Also you shouldn’t use game graphics or official artwork because that’s directly stealing from the source material, that means class icons are a no-go too unless you also plan to give them the same treatment as the logos.