Nice redesign. Reminds me a lot of Cooler from Dragon Ball Z (though I doubt that's what you were going for) I agree with your description in your Dark preview image that he should've had his own design instead of just being Shadows shadow. Since this one seems to have been uploaded earlier than the other Mephiles pics you made, I'm assuming that this is the earlier one, but in all honesty I like it more, mainly for the additional armor and tail spike. All are awesome either way.
True true, especially if he does what a lot of typical villains do (go through multiple forms)with the in game forms being his first (since they're interchangeable) your redesign as the second, then this more armored form as a final. But perhaps that's just the way I think with linear form changing. Either way, very nice looking.
Also, I wished Solaris was redesigned, for as cool as he looks (specially in his second "Hyrule Crest" form) I don't see how a Shadow/crystal being merged with a giant lava monster equals an ethereal god thing. Dark Gaia from Sonic Unleashed looks like a better fusion to me. But I digress.
And well, he is a shapeshifter so I guess he could morph some extra armor/spikes if he needed it.
Also, I wished Solaris was redesigned, for as cool as he looks (specially in his second "Hyrule Crest" form) I don't see how a Shadow/crystal being merged with a giant lava monster equals an ethereal god thing. Dark Gaia from Sonic Unleashed looks like a better fusion to me. But I digress.