The idea is nice overall but honestly the texture wrapping leaves a lot to be desired:
The Naga dragon, the one that to me looks like the best of the bunch, has a stretched wrap around the muzzle area, which wouldn't be so bad if not for the fact it's going to be constantly visible through the Portrait animations
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The Demon one's wrap is very badly stretched around its neck (where the chains are) and it's pretty bad to look at (I would also suggest to move the chain texture further up, after the fin ends, so you could make it look like a chain collar of some sort). Also, as Dreadman pointed out, the fin itself is a fleshy mess atm, that might be fixed by using a different texture (Red Dragon's fin, maybe?), though if I were you I'd try and change it to the one Lightning Lizards have (and then tweak it so it fits with the model's proportions... and change its texture too I suppose)
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Then there's the Frost Wyrm one, setting aside the fact that I don't see it being very useful as vanilla Frost Wyrms exist because that's a "me" problem, this one suffers from the same issues as the Demon Dragon and more as his upper torso is also kind of a mess as far as I can tell.
The rest of the main body up to the tail doesn't look that hot either, the tail itself seems to be using up a large portion of the texture and what's left has to cover for the rest of the body, I'm pretty sure if you were to stretch the part of the texture you're using just for the tail so it also covers a good portion of the lower body the overall wrap would improve.
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I think that fixing these spots would greatly improve the models' quality. Give it a thought if you can