Kat 14second E cdr nerf only affects inexperienced Katarinas (bronze).
With 10% cdr (runes+masteries) and/or 2 points in E, the nerf does not do anything.
I suggest you make a stronger nerf. For example, put E on 20 seconds and/or make E unaffected by cdr and levels.
I one-trick Kat, and honestly, this nerf is really not effective. I cannot emphasise enough that Kat is exactly the same and still one of the best mid lane champs at all elo AND competitive. I want to voice my opinion that this nerf is actually lazy. and that you should put serious thought in nerfing her kit, or her ban rate will stay the same. It's also misleading as bronze 5 Kats will never pick her up, due to lack of knowledge of cdr. confused as to why people are super good on kat.
Sorry if this appeared a very slight rant, but this is what I honestly feel after spamming Kat today with no feeling whatsoever of the nerfs. There is a 1% chance that people on PBE have probably mislead you if they did not point this out. Even Scarra said this nerf does nothing.