The sky lords are the ones who took the ancestral dragon out of the world, and they're the only ones who can take it back. The only problem is that the sky lords don't have the means to take back the dragon by force, so the only way they can do it is by force. The problem with the tower is that it's sealed with the soul seal, which means that even though the girl is still alive she's just as dead as before. This means that she can't go back to normal until someone removes the seal. This is a tricky problem to solve, because the girl will have to marry the sky lord to do it.