Just wanted to highlight this post from the US forums for visibility:
Hello everyone! Thank you so much for your ongoing feedback about the Mage Tower.
We are currently evaluating the data regarding Mage Tower success rates, and we have identified that some of the challenges for certain specializations are more difficult than intended. We will return once we have more information to provide on what changes we have planned to bring those specializations more in line with the rest.
Thanks all and best of luck to everyone still battling away in the Tower!