No huge difference from their human form. Perhaps a goat changeling begins to notice the beginnings of horns sprouting from her head as she's brushing it in the morning. A Fireheart's pupils shines with the brilliantly haunting fires that burned away his flesh in Arcadia. Small cosmetic changes that mark the birth of a changeling, and the death of a human.
The ram's horns have grown completely now, the hair on her arms and legs is more coarse then it used to be. The Fireheart can trace every vein under his skin, because each of them seem to glow red from within. A tunnelgrub finds he cannot stand the light, and his skin has not only turned a pale white, but every so often seems to ooze a strange mucus. The changeling is leaving more of their humanity behind. Most changelings are around this area. They've been away from Arcadia long enough to have an understanding of the wyrd and how it effects them. It's easy to tell them apart from a human.
The ram's arms and legs are now covered in a thick fur. Her horns are sharp and glisten with icicles that never quite seem to melt. The Fireheart's hair is a torch of flame, a beacon to others changelings that he's no longer the poor weakling he once was. He's ready to take up Summer's banner and become the hunter. The succubus' skin has turned a pale red, she never seems to need to apply makeup and a thin demonic tail flicks behind her every now and then with the slightest hint of amusement. Changelings at this wyrd are stronger for it, there's no denying that, and the wyrd has changed them accordingly, sharpening tooth and claw, exaggerating features such that they begin to resemble more closely the strange beings of Arcadia.
A tiger seeming finds her body all but covered in silky red and black fur, her face, chest and stomach the only areas to have escaped the eerie transformation. Her hands have warped into the vicious claws that scarred her husband horribly after a terrible fight one night, driving him away from her. She possesses sharp fangs, a long tail and eyes that speak of a frightening animal inside, just waiting to be unleashed. A woodblood dreams of Arcadia and being swallowed by a living tree, only to wake up and find that his skin has been replaced by a thick layer of bark, flowers and weeds fight for space, twining around his form as he fights to forget the horrific images of the night. Changelings at this wyrd are far more rare then not, and usually they represent a struggle. Frailties have formed and the changelings find that they're frighteningly close to the Fae who more often then not they still despise. Changelings at these levels are usually struggling to maintain clarity, and their place with humans.
The tiger has shed nearly all of her humanity. Mortals become fearful in her presence, even if they're not sure why. Her claws are large and sharp, her body covered head to toe in fur. Her face is a cruel blend of human and animal features. She has a flat nose, sharp canines poke out between her lips, and her eyes have lost very nearly all sanity. The woodblood almost looks more like an ent then he does a person, moving slowly, the sound of splintering bark can be heard when he sits and on his every breath the whisper of the leaves through trees is carried. The fireheart's skin smoulders and burns, forever part ash, part flesh and bone. Though he no longer recognises the face of his parents and his human friends, he cannot help but remember the terrible burning of stench that assaulted him in Arcadia. It's rare for a changeling to remain of this wyrd for long. Whether they are abducted by the Fae, or mistaken for one and murdered by their fellow changelings, their life is hard and their humanity all but gone.
NOTICE ON TAILS
Tails may be equine or caprine, feathered (like a Peacock) or smooth ('Devil tail' or snakelike, feline or canine). Common sense must prevail: there are never any Changelings who are basically snakes, nor can a PC have a tail so long that it would not be concealed by the Mask. In addition, this tail may not grant any mechanical bonus or give you any extra actions; they cannot be used in combat. It is purely cosmetic in nature, and not strong enough to use to pick up items larger then a pencil. Furthermore, all tails are still subject to staff approval.
Core, p. 27: A changeling's mien almost never changes so far from the changeling's original form to make him unrecognizable. He may grow or shrink a few inches, but he is very unlikely to gain or lose a foot or more in height. Hair and eye color may change, and facial features may subtly shift, but the appearance of the stolen human is never completely over- written.
RoS p67: * The Mask Conforms to the Changeling: If an Ogre's mien is that of a seven-foot-tall, 350-pound troll, the Ogre's Mask makes him appear to be a seven-foottall, 350-pound brute of a man. Think of the Mask as a second skin that covers the changeling's true appearance: the Mask can make allowances for minor variances in form, for example, hiding horns or claws or a fiery aura, but the Mask does not drastically change a changeling's apparent physical form.
Equinox Road, pg 12: A Snowskin is human, early on: maybe just an icy breath and a bluish pallor. But as time goes on, her Wyrd evolves, and her mien evolves, too: her flesh is now a spider web of blue and broken blood vessels, her eyes are frozen marbles in her head, her breath casts whorls and gales of snow, and every inch of skin is covered by a crusted frost like you might find on some ice cream that's been sitting in the freezer for far too long.