A few years ago I was really into learning about mythical creatures from around the world and I remember being intrigued by one in particular, and recently I thought about how well it could fit into the game.
First- an introduction to the creature. It's called the A Bao A Qu. It lives at the steps of the Tower of Victory in Chitor and waits for someone to begin ascending the tower. At the beginning it is translucent and shapeless, but when someone begins to climb the tower it gains strength from the person climbing, drawing its life force and changing color and shape. When the person reaches the tower, it is said that the A Bao A Qu will reach a final form, though no one (or only one, myths are contradictory on this sorry) has ever achieved the feat, for none were perfect enough to complete the journey to achieve Nirvana.
I personally feel that this myth is definitely suited for a tower in Wizard101. While I can't think of bosses for each level and stats at the moment, I might post a reply on here about that later, or you could help me come up with it. I just think it would be interesting to do a tower where every battle has a creature watching you make your progress from the corner, slowly growing, solidifying, and taking shape, and when the battle ends it disappears until you fight the next battle on the next level. I am also unsure on whether it should necessarily be a monster to fight or something you release from the bonds that hold it to the tower. Either way it would be fun to see how this less-known myth would translate to Wizard101.