As you read the alien, mind-twisting words they vanish from the page. Your vision blurs, and you feel as if you're flying right out of your body. When you can see again, you're looking down at a tiny pink hairless ape. It's on all fours, and is making a funny bleating noise. You can't help laughing, but as you do a torrent of flame roars out of your mouth and incinerates the ape.
It's not long before you notice that you're not what you were. Dragon claws, dragon scales...no question about it, you've somehow become the dragon. And he must have become you.
On the plus side, you've won the treasure. On the minus side, you're too big to get out of the cave. The spell book is ashes, and in any case the transmogrification spell is already used up.
There's not a lot to eat around here. Not much except...
Actually, you make a very tasty roast.