I just hit this guy at about 25 as well (Don't remember the exact level). It was pretty easy for me, took two tries.
How I did it:
As soon as the fight starts, flame both Nest Towers. Then immediately fly to the safe-point at the top of the map so that you can heal. Save after you heal. Then jump down and the game will automatically turn you back into a Dragon, and take care of him. I did it by circling him flaming, and then used the Fireball once the cooldown is over.
