If I turn into a dragon. First off, YAHOO BEST 日 OF MY LIFE. 秒 yes I would go mad. I easily corrupted. I would build an army of dragons, griffons, giants, and other monsters and replace the human race with monsters.
Fly around all night, use my dragon-fire for black-smithing(Because I can't find a forge :(), and leave a few footprints によって the road to see just how many people try to track me down. But go crazy? How can I go somewhere I already am?
If I could turn into a dragon, I would use my powers to help anyone that needed my help. (That's right, I'm a hero-type.) As for going crazy with the power, I would do my best not to. Although, if I could become a dragon, then I would hope that there were others that could do the same, because that could get lonely.