Hello! This is my first build guide on my absolute favourite champion! Note my epic Canadian spelling too :). I always build Kha'Zix like this for jungling just because it is overpowered and gank's are excellent!

Pros

I pick exhaust instead of flash and ignite because you don't need flash to run because you have your E and ultimate. You don't need ignite because you do enough damage so exhaust just doesn't let your opponent run away :)

His q is what makes Kha'Zix so special! It truly deals tons of damage and is on a short cooldown. Evolve his Q first... then his E. You can choose between his W and R last. His W provides a bit of cc with his passive... But taking reduced damage and being able to use your passive repeatedly 3 times with his r is even better... So I usually get his R.

For jungling... And even playing Kha'Zix normally, you have one MAJOR rule. ALWAYS HAVE BLUE BUFF OTHERWISE YOU RUN OUT OF MANA INSTANTLY. Thats whats super annoying about him. If he can't use his q and his w then hes kind of screwed. I start with wolves... then get a leash for blue. Here is the jungle path: Wolves, Ancient Golem, Wraith's, and if you believe in yourself... Elder Lizard, Golem's, and make your way back to the wolves. You can counter jungle quite early because Kha'Zix is an excellent dueler because of his passive.

Okay. This guide may be terrible but it is work in progress and I hope I can learn more about how to do things on this site :) I hoped I helped you!