How to Fix Ryze

I just watched the Patch Rundown and noticed how Jag wasn't really taking Zirene's player experience into account in the case of Ryze. He just sort of said "Well we want him to Root infinitely" and I don't find that okay. So I came up with an idea on how to correct Ryze.

How to fix : Every time he recasts W on the SAME target, make it a slow, decreasing in potency. Example: Cast One - Root Cast Two - 60% slow Cast Three - 30% slow etc.

With the movespeed he gets from his ult, this should be reasonable, giving him that Machine Gun feel but without giving people 0 chance to do something about it.

Also it would allow him to Root multiple people but not the same person repeatedly into death.