Though adult bunny dragons are finished growing physically, some are not finished growing magically. A large majority of bunny dragons have only enough magic in them to exist, and no more. Budrages are able to unleash the powers of the elements, for good and for evil, whatever they choose.
The budrages are chosen or revealed (it's never certain which) by an extremely secret ritual referred to only as The Trials. When these trials occur, all eligible adults will be invited to participate, though an adult may only try and fail three times before it is determined that there is no magic in them. There is no shame in failure, as the majority of dragons are not capable of becoming budrages. Only two in every five dragons are able to become budrages.
When a dragon becomes a budrage, a Gehenian (or two, or three sometimes) chooses to live with them. These creatures do not count as bonds, but rather as companions who will lavish the dragon in attention or, more likely, annoy the crap out of it. Gehenians are special little things who will gladly chatter on for hours while performing the most menial task. Some of them have vicious senses of humor, and will push a dragon or its bondmate just a touch too far. Gehenians are generally the size of an outstretched palm and can teleport in a puff of sulpher. What they eat is not known, for they're never seen to consume food or drink. Where they go when they're not with their dragon or on an errand is also unknown. They keep largely to themselves about stuff like this.
Each budrage has a specific type of magic over which they have control. There are many varieties, though very few have been revealed thus far.
Revealed types of budrages:
Terrestrial - Controls earth, plants, stones, caves, masonry, etc.