Kha'Zix, a champion I would like to see buffed

I used to play Kha'Zix a lot, and he was a really fun champ. However in his current state, he feels lackluster. I feel like would be more fun if just his Q, R, and evolutions were changed.

His Q evolve lacks any sizable boost unless the target is isolated. After his first major rework, they solved this by giving it percentage damage. This was a problem because it made him too effective vs. tankier champs. In the current incarnation, it only functions when they're isolated, which is not good. A solution to the problem that would require some balancing would be a style execute, increasing based upon how low the target's health is.

His W in the past has had different problems. Originally it was amazing at wave clear and poking because it would apply his passive. However, it is currently just a barrage of spikes, with a slow strapped on. An idea that occurred to me recently that would fit his ambush playstyle would be if once evolved the spike were similar to buckshot, dealing increased damage if they hit the same enemy multiple times.

His ult is also a little boring. Right now it is mostly just a stealth, if they reverted the removal of the damage reduction, (Only slightly, maybe 30%) Along with adjustments to the inter stealth cooldown. One idea that I also came up with is once the R is evolved, it behaves like Akali's ult, in that is has charges, and you can use a charge at a time. Note that there would not be gains upon kill or assists for this, unlike Akali's ult. I think a combination or one of these would make his ult more fun.

Thought's or ideas on how this could be balanced and used to help Kha'zix out? I would like him to get something at least. And trust me, These would have to be fiddled with to be balanced, as the way I suggest them, I know he would be too strong. He does deserve some buffs.