Certain champions i feel could be cool with that dnd touch
not dragon trainer skins
actually draconic skins
Renekton: top candidate, actual dragon, not croc based
Brand: Firebreathing dragon, just because
Rumble? because rumble!
Gnar, where he's a little cute lizardman and then a dragon
Chogath, void spikes become dragon spit
Twitch: as a little kobold
Kog'maw... wait he already has one
Riot mainly makes skins based around the idea that the skin fits the overall "theme" of the champion in mind. I say mainly because that doesn't always apply, as they sometimes give skins willy-nilly to whomever they want.
Example of the former:
Mundo here is a big, hulking and buff guy. So, he's been given at least two "Buff Guy/Bodybuilder" skins. Mr.Mundoverse and El Macho Mundo being my cited examples.
Example of the latter:
Ekko, not long after he was just released, was given an Academy Skin. Go to the post, and you'll find comments to that effect on the subject.
But back to your post. I like the idea of draconic skins, as it can give certain champs who might not have much "fantasy" feel to them (Fantasy of course being a important part of Runeterra's lore/concept). There are probably countless skin-lines that could fit with all the champions out there, but all we can do, sadly, is make suggestions and hope Riot notices them, just like you are doing with this. Good Work, Sir!
[slayer-pantheon-thumbs]
I like 
,
, and 
Add Annie (I know she has tons of skins but this reminded me of something I saw years ago called Dragon Annie), Anivia, Corki (he has a dragon rider skin but I think his abilities would work for a Dragon)
