Setting up a shapeshifter

I need some help in setting up a female shapeshifter I am working on. I need some help in make the description human form fit with D&D. How do make the character where in it canine form it can fight supernatural beings? How do I make the canine form's description more original but it have the description be that of monstrous three headed dogs with an obvious wolf ancestry. What things should the canine form and human be able to do?

What if the canine form's physical attacks deal damage normally against incorporeal
creatures, regardless of its bonus.

Human Form: A petite Chinese woman walks in, moving with grace. She is muscular in an athletic way, sleek muscles rippling under her brown skin. Her lustrous curly bubblegum pink hair that is parted down the middle descends down to her elbows. Her angelic looking face is wide at the temples and hairline, narrowing to a small delicate chin. In both of her pointed ears she wears four aquamarine earrings. Her perfectly shaped bubblegum pink brows lead to her perfectly shaped narrow nose and thick lashes that bat sweetly over her bubblegum pink eyes. Her eyes pierce you as you gaze into them. Her lips are bow shaped. She stands with elegance; she is at home wherever she is. A formfitting brown motorcycle jacket with lowered zipper shows off her attributes nicely. A very toned and very tight belly with a silver navel ring topped off by medium-sized breasts encased in a pleather zipper front cropped top. Her right and left arm each hold a long sword. She wields both weapons in her arms as if they were extensions of her body. Her very toned and tight buttocks and waist are encased in a pair of tight blue jeans. She wears a pair of black steel toed boots that reach nearly up to her knees.
Canine Form: The Barghest is a huge monstrous three headed female dog with obvious wolf ancestry. She stands five feet tall at the shoulders and measures ten feet in length not including her tail. Protruding from her back are a pair of huge leathery wings. The black hair on her body is rough and hard and is especially wiry and long over eyes and underjaw. Her eyes are so deep and dark you could see death in his soul! The long muzzle is wedge-shaped. The glowing steel-like teeth lining each of her head’s large, powerful jaws resemble the teeth of a hyena. Around each of her neck she wears a spiked dog collar. The front feet are round, compact with well arched toes, turning neither in nor out. The back feet are somewhat longer than the front feet, turning neither in nor out, equally compact with well arched toes. The claws are shaped like hooks allowing her to shred and tear flesh.