User blog comment:ClariS/Why Xerath's Passive is Bad/@comment-6271162-20130319165358

While I agree with you that the Innate is somewhat off on Xerath, I disagree that it does not go up with his lore and theme. After all, he is being of pure arcane energy, so you shouln't be even able to hit him. Bonus armor simulates this nicely, as it is impossible to completely prevent all physical damage dealt to him.

Also, I think that the Innate was not intended. Xerath had a different ability during his development, but due to some reason unknown to me, they removed it and used this one because of lack of time. I recall some Red posting this on the forums...