Huh-- I made one recently with that trait ^^; the only traits that are "free game" are the ones on the common sheet, fluff traits are and always have been regarded as mutation, which is now classified as 'special' (because I thought that sounded nicer) and special encompasses everything not hard classified in the common / rare / super rare charts. The reason the special examples only include a few visuals is because the possibilities are endless and I wouldn't be able to fit absolutely everything on a sheet / I'd have to keep adding them for every new thing I decided to add.