How I would change Kha'zix :P
Kha'zix is one of those champions that has had very high highs in his day as one of the top tier mid laners of his time but then he was reworked/ nerfed so hard that it seemed logical that he should now go to the jungle...players then found a build path that they could still use to make him extremely powerful he was then subsequently nerfed again this time to the point where he is rarely seen and can barely carry a game even if ahead.
My proposition is that most of his nerfs were entirely because of the isolation mechanic that he has and the hidden power that it provides when the enemy is not around his or her teammates/minions/ tower. The question is if that is the problem why has it not been scrapped? It is not really part of his identity we have his evolutions for that, its not really doing anything for him as it makes it abundantly clear which guy he is going to be trying to assassinate and it just feels like its not a big help to his overall philsophy.
My proposition for this is that we completely scrap the isolation passive so we can give power back to Kha'zix in other meaningful ways while making him a healthier champion overall. My compensation would be to change the evolutions he has so they are now more consistent with his fantasy of being a void creature that adapts and overcomes any situation no matter what it is.
Now for q this is prob the easiest thing to buff/change I would just make it so when he evolves it it becomes slightly more powerful at all points but make it so he does double dmg when a target is low health so he can still assassinate but it is a much more consistent assassination pattern that what he does now.
Now for w the biggest problem a lot of people had with it when it was nerfed is the range it had on it and the amount of utility it brings to the table. For this change i would shorten the range of his w to around the range of his evolved claws but also make so when he evolves it it can now hit with all 3 spikes at once.
His e for me is almost as good as it should be but I'd make one small tweak to it take away the entirety of the dmg it provides. Because with all of the changes I have made it should be more then enough dmg to assassinate someone.
For his r i would just put a 10% dmg reduction on his stealth and call it a day on it.
I hope these changes bring to the table of what I'm trying to accomplish with him and I welcome any critics or beefs or what have you that may come with this rework :)