Kha'Zix change idea

make his passive scale with bonus AD, and increase the slow (maybe from 25% to 40% or something). The passive scales off of level and with AP, and does magic damage. Nothing scales off of AP on his kit except the heal on his W.

make his ult a charge system.

make it so you can evolve every ability, not 3 of 4. like start the game with 1 ability that you can evolve. maybe start with lvl 1 on your ult and 1 charge. (something like nidalee or elise)