You place your hands on the book, closed your eyes, and said the command:
"Shift."
Almost immediately, you reopened your eyes to reveal pupils that had turned golden in color, a sign that the transformation was beginning.
Excruciating pain flooded your nerves as your body began to stretch and contort into a whole new form altogether.
You look down at your hands to see that were quickly starting to gain mass. You uttered a startled cry as they shifted to large paws. The fingers compact in on themselves, your joints and bones melting together to form the front toes. Like springloads, sharp, dark claws appeared in your nail beds.
The pain was most intense when you felt your skull stretch outwards, like someone was tearing your nose right off your face. Inside your jaw, it felt as if your teeth threatened to burst from your skull.
A low growl came from your throat, hardly even human at this point due to your quickly forming muzzle.
You screamed in agony as massive canine teeth grew from your gums. As your muzzle continues to extend, your voice dropped multiple octaves with every breath, to the point where you couldn't speak anymore.
Your shoes snap apart as your feet outgrew them, though they looked far from human feet any longer. Your front claws mar the floor, trying to endure the feeling of your bare feet shifting into massive paws.
Your arms and legs increased significantly in diameter as muscles grew in. Small rips start forming on the sides of your pants as your thighs bulked up.
Each breath was expanding your chest outwards your ribs creaking as your increasing size began stretching your shirt to and past its limit.
Your clothes begin to tear apart and your skin burned as thick, coarse fur sprouted from your pores. The fur was red, pockmarked by black spots like those of a leopard. A growth of thick fur formed a collar around your neck.
Your spine popped, the hips cracked, and you drop to all fours, your body taking on a quadruped stance. A bouquet of five feathered tails stretched behind you, increasing your mobility and balance.
The pain begins to fade, save for a migraine that formed int the center of your head. You didn't expect the change to be that painful!
Your claws clack against the floor of your home, making a noise like stones striking one another. You move around, trying to work out any lingering aches and pains, and get a feel for this exotic new form.