Top left is the basic form, which has a rodent and canine base to it. It's the smallest and weakest of the forms, and is the most common form.

Bottom is the attack form, which has a unicorn and deer base. Adults have three prongs on the horn's tip, and they use it like a bayonet. They can be ridden like horses, and are able to carry two full grown men on their backs with ease.

The right is the flight form, which is seldom seen except in legendary depictions of the goddess Celestia riding them from the heavens. They are based upon the Quetzalcoatl. Flight form is very long, with four powerful wings. They are said to carry about 10 grown men with ease, and are able to fly very fast. Celemera have no natural need for this form, and as a result, this form is hardly seen in the wild.

Celemera © Me