And you break your promise again. Tsk tsk.
I have yet to have anyone give, in concrete, indisputable fact that WT is OP. Good cards aren't always OP, and not every card has to suck to be balanced. What makes the Wizard so good (not the WT, btw) is the Voltaric shield, coupled with even a couple of points of armor. This, in conjunction with the birth of spells the Wizard is trained in, as well as the inherent attack spell that he can cast, makes him extremely powerful. This does not mean that the WT alone is OP, nor does the free action, nor the changing of spells, nor the mana generation. Correlation: The Wizard is too powerful. Let's nerf another card we don't like. Out of the games I have played with your fabled "Dark Destroyer" none of them has been affected by WT. It was shot once. And it pushed and slammed a creature. Any other time he just used it to attack with himself, WT, and then QC inherent zap. There are a few things about the Wizard I do not like, and do not see being good for the game, but no, the Wizard's Tower is not OP.
Now, unlike sikE, I have nothing more to say on the matter.