I know, I was arguing against it being a part of a normal spell school there. It might make sense as Docakhiin, I just don't personally want it, since I think it would be an overpowered ability, and be hard to program without it looking bad or working bad.
how about making a dungeon for its acquisition, not just any dungeon, a fixed level 50 dungeon only unlocked at the later stages in the game.
if a player wants such an ability, he has to work for it.
your dragon form power could be something like this:
-able to fly
-biting for melee attacks (can't block while flying)
-as a dragon your only form of ranged attacks would be from dragon shouts (no magic and of course no bows)
-a timer for your dragon form, you could extend the timer by charging the shapeshifting dragon shout.
-physical power is a bit higher than your normal form but dragon shouts power would be unchanged as those are fueled by your soul not your body.