Ultimate Mega Dragon is a type of Dragon in Club Penguin. Members can transform into them at Medieval Party 2013 by mixing potions. Their scales are as hard as any knight's armor, they can fly around and have the ability to breathe fire.
Trivia
You could not 'throw' fire in your igloo.
You could have walked your puffles while transformed into the Ultimate Mega Dragon, although they will become invisible until the spell is reversed.
It was the last transformation in Garianna's spell book.
Unlike the Pteranodon transformation, you could not fly whilst you were transformed.