Wrong masteries(+ what morrivar said), why would you put 4 points at Fury when the cdr is better a lot better on kha'zix, also i don't get why to take 1 point into Spell Weaving and Blade Weaving instead of the sweet 6% armor pen from Devastating Strikes .

The build is pretty standard, really nothing to say there, except that you did not upgraded hexdrinker into malmortius againist APs, i dont think banshee's and ga are needed always and togheter. Same for randuin's and ga againist ADs.

About the runes, what the hell? Crit chance seals? Crit chance runes aren't that great, as seal they are even weaker and on kha its just useless, plus you are denying some very usefull armor.

Those masteries aren't possible. Can't put a point in Unyielding in defense without 2 points in Block.

I would suggest trading the ionian boots for swiftness or tabis (or even mercury to throw in some mr) against heavy ad team. With BC and FH you already have 30% CDR, you will mostly have access to blue buff, so that will make your 40% CDR. You are "losing" some gold there. Or you could may be trade them in lategame. Feel free to rebut.
GL! HF!

cool guide! I, as the commenter above stated, am getting Kha'zix, and this guide really helps! I'm excited to try it out!

Thanks for checking it out! Let me know how it goes?

I look forward to using this build,I just bought Khazi and cannot wait to use him. I switched around the around for the Core Items a little bit to go with what I felt made sense for me, but great build :)