I think I may have a partial answer for you. werden +zu specifically means to transform into, to change into, to become.

Now, what I don't know, is if there is a gap in meaning with an expression such as wird selbst ein Drache, or if it's just a question of style: to me wird selbt zum Drache sounds more stylish and poetic, don't know if it's just my ear playing tricks or if it's really the case. Luckily, I'll see my teacher tomorrow, so I'll ask her ;-)