Azir, and his death.
First off, Azir was pretty good. He had mobility, ap, and could burst down any target. But, this nerf will kill him. Riot could have taken away his shield, and only the shield. (That would have been fine.) But they had to remove the knock up. In my mind, Azir's knock up was the only thing that was really good when it comes to his E. I love how he can e q to a soldier, and drift, but removing the knock up? And then they had to nerf the passive. It was perfectly fine. so I don't know why they'd want to nerf Azir.