WOOO! Official refference for his true form! O3O Strap yourselves in, cuz big description is on the way(hope that's the right figure of speech for "hang on". XD)

Usually this is where he'll the most focused and serious. The facade drops completly now, both mentally and in his abilities.

Physical changes: His chest broadens out and his hips thin a bit, the exact opposite of the human-like disguise. His figure builds as well, although not excessively, as muscle shows much more frequent now. His claws on his hands are now in both arms (while before it was only on the demon arm). Skin is replaced by tough and quite resistant scales. Powerful bone-like spikes cover his face and chest to protect weak points. Somehow gets even taller, faster and stronger.

Ability changes: While his mystic powers remain unchanged (as the destructive power relies on which spell is being cast), his demon powers are enhaced, as he can give his shadow a physical form for much longer than before (the 3 minutes now change to 30). However, he now gains access to the main Mefalon ability: fast recovery. Small wounds heal up quick, and he's more likely to resist critical blows and fatal wounds if he can find a place to heal up.

Wings: Powerful enough for Flight, can carry someone else with him (although that tires him much faster than normally). Very resistant, and can often be used for shields, but also sharp at some points to be used for weapons.

Tail: Just as strong as it was before, although the tip can now be used to pierce enemies. can carry someone if curled around them properly.

Weaknesses: Shares both mystic and demon weaknesses at once, them being magic sealing/draining artefacts-which also disable his healing temporarily (Mystic side) and light based attacks that, noy only blocks his shadow, but also blind him for a few moments (since his senses are enhanced, he's more vulnerable to light).

When will he transform: Usually at times where it is absolutely necessary, such as a very powerful foe that he can not defeat with any other form. But there will be RARE exceptions, where he'll usually do it for close friends. And Although he dislikes it, some people make him feel a bit more comfortable while in it.

Mental changes: More focused and determined on his goal, often will not take unecessesary strategies and goes directly to the objective. He's calm, in control and a bit less joke-y about situations. But while not with any problems, he'll be a bit more cheerful.

WOW, that was long. who read the whole thing though?