...You know, I have to be honest: Kha'zix doesn't seem very "adaptive".
Why not give him the ability to like, spit acid for range (cass), or generate a harder shell for defense (rammus). What about flying over walls? Or regenerative abilities? Or increased mana regen? Maybe you could have him do something really new and, say, burrow underground! There are so many things that you can do with this guy, and yet he's just going to get cast as a rengar clone due to the stealthing and leaping. He's just another stabby assassin.
Overall, he just feels like an ambitious project turned lazy. I get it, you only have 4 keys for abilities, but if you're going to make him "adaptive", you have to find a better way to make those interchangeable. He has a lot of potential, I'm just sad to see it...well, wasted, really.