Hey there mobafire, this is my 3rd mobafire guide. Now before we get started i just wanna say that this build isNOT FULLY COMPLETED AND WILL BE UPDATED ACCORDINGLY. Despite what people say, that Kha'Zix is NOTHING at all like Rengar. Yeah they are both assassins but if rengar gets into a fight with 2 or more enemies, he will die eventually but a skilled rengar will be able to kill them both no problem taking only minor-intermediate damage. However, Kha'Zix is designed just like Talon in the sense of he doesnt need tankyness to survive, he let's his kit protect him, and thats what you do with Kha'Zix

tl:dr; Don't downvote because my guide is not fancy like the others, im still learning the BBC code.

Pro!

Incredible Burst!
Epic Towerdiving Ability
Better Than Average Clear Times
Absolutely Destroys Single Targets
He evolves
He's a VOID character. Kudos to Riot!

Con's

Ultra Squishy
Require's a LOT of practice
Does not fit meta (no one cares bout the meta)
1 stun and he is done
you have to let your team fight without you until someone peels
off for you to actually do something
Very Underrated Champion, like all assassins

I know what your thinking: "Kha'Zix too squishy OMGWTFBBQ NOOB NOOB *downvote*. Dont get any ideas just yet. How many people have you seen build Talon like a tanky bruiser? Yeah he lasts longer in fights, but his damage is greatly reduced compared to a Talon that completely abuses his AD. Kha'Zix is the same thing.

I take the following runes:
Greater Mark of Attack Damage
Greater Seal of Armor
Greater Glyph of Scaling Magic Resist
Greater Quintessence of Attack Damage

These runes give all your abilities a nice little chunky burst of damage while jungling which increases your clear time. I only take a little bit of armor to supplement my cloth armor. Despite Kha'Zix being squishy, since you cant make the monsters do any less damage to him, you may as well increase your own damage, am i right?

-ADD IN MASTERY DISPLAY HERE (little help here perhaps?)-

I take 21-9-0. Yeah i know i didnt get the upgraded buff duration but honestly, you should be counter jungling and ganking like no tomorrow. I maximise the damage in the offense tree whilst taking cooldown reduction to help you spam Taste Their Fear more often while clearing.

I also take 9 in defense over utility because of Kha'Zix's squishyness. Nothing worse then waiting for a gank so you go to golems and they accidentally kill you.

This section is a work in progress. PLEASE DONT DOWNVOTE FOR THIS

I can NOT stress enough how important ninja tabi is on Kha'Zix. The 10% reduction on basic attacks is really really nice.

I have tried starting with all kinds of items to begin a jungle run. These include:
Long Sword
Vamperic Sceptre
Boots
Cloth Armor

I found cloth armor to be the best since it helps me not be as squishy keeping me healthy for low level ganks. butYOU ABSOLUTELY MUST BUY NINJA TABI ASAP OR YOU WILL DIE

CORE BUILD:
Ninja Tabi
Doran's Blade X 3

Yes thats right, i said X 3. THREE DORANS OMG NOOB!!!11!1!. No. Dorans gives kha'zix everything he doesnt have. A decent health pool. Also, 2 is not as good as 3.

From here, work on rushing Bloodthirster starting with either a Vamperic Sceptre or a B.F. Sword Depending on how your jungle run is going, but we'll get into that later.

Mid Game Item Summary
Ninja Tabi
Doran's Blade
Doran's Blade
Doran's Blade
Bloodthirster
B.F. Sword

From here you can do 2 things, you have go another BT or an IE or a Cleaver. Its personally preferrence at this point. I have yet to try cleaver out but IE and a 2nd BT both work really nice.

-TO BE UPDATED WITH FURTHER TESTING ASSUMING A GAME LASTS LONG ENOUGH-

Ok so for skills, as above i max Taste Their Fear first. Now the heal on Void Spike is nice, but you should try and spam it as much as possible while clearing.

TRICK: You can cast Void Spike Mid Leap which is awesome for picking up a kill who just popped their Flash to try and escape you

Depending on how the game is going, and which skill i evolved, depends on whether i max Void Spike or Leap first. But Taste Their Fear should ALWAYS be first.

Never EVER put more than 1 point into leap until it forces you to

Smite Flash
Exhaust Smite (TO BE TESTED MORE)'
Smite Ghost

Smite & Exhaust are your best friends. Mainly because if you need to close distance because the enemy just popped their Flash you have to catch up to apply your Unseen Threat.

i have also found that Ghost works nicely too because it allows you to catch up to that target who is just 55 Hp off dying or you just want to book it out using your void assault.

Exhaust is now (as of 13/10/12) my new favourite secondary spell on jungle kha'zix because it gives him that cc he is missing until level 6.

-Yet to find a jungle route picture for kha'zix as i am a horrible artist-

Kha'Zix is VERY dependant on the Crest of the ancient golem and the Blessing of the lizard elder to be effective. Whether you have to steal it from the enemy, i dont care but you NEED those buffs.

Personally, my recommended action is the start at the Blue Buff and then have your mid laner do the "Pro Leash" by making the golem confused OR get a hard leash so you take almost NO damage.

From here, if the enemy jungler starts blue, invade their red IMMEDIATELY and make sure you have Void Spike ranked up. Launch a spike at the Red Buff and make all the creeps go into the top brush. Hiding all evidence of the buff being taken. And yes you want to clear the red buff because the enemy will have no idea when it will spawn again so you can just keep taking it without them knowing.

From there you want to Gank Top and secure a kill. Whether that means saving your ally right before he dies, you NEED that kill to rush your Ninja Tabi. Your ally MUST instigate the fight so you can run in as you dont have a leap yet.

As usual just keep roaming your jungle until someone is overextended or something so you can continue to get fed.

NEW DISCOVERY: It pays to have your team lpay very cautiously until you reach level 6 so you have your evolution point into Void Spike This allows you to gank more effectively. If you team is being roll'd hard, then help them, otherwise, stay in your jungle.

There is nothing better than seeing the enemy AD Carry wandering around alone. But this is not without risk, but it is certainly delicious!

If you do find the enemy carry or squishy jungler alone this is what you want to do.

Doubt's Step by Step guide to Devouring Solo Targets. PRE LEVEL 6

Step 1: Run at them and apply Hidden Threat then Taste Their Fear
Step 2: Follow up with a Void Spike
Step 3 (OPTIONAL): If they flash, leap after them NOTE THEY MIGHT GET AWAY. DO NOT CHASE THEM IF THEY DO ESCAPE. They burnt a flash, thats a win

Step 4: If they do not get away and they are running near bushes, make sure to weave in and out to get your passive up

DUELING POST LVL 6!

1. Use your spike racks to slow and deal heavy damage from brush.
2. Basic attacks and Taste Their Fear
3. If you start taking heavy damage, use Void Assault to negate parts at a time while hitting them safely in the 2 seconds between each stealth charge

-TO BE UPDATED LATER. NEEDS MORE TESTING-

Everyone should know how to juke. It isnt difficult. Here is a quick list of some tips and tricks for escaping your enemies.

Tip 1: If your being chased into a bush, quickly assess if you can kill the target., if not, activate void assault in the end of the bush and stay still, they will think you have ran ahead of yourself, when they pass out of the bush, turn around and leg it to your tower.

Tip 2: If you are being ambushed by 2 or more peeps, try to combine Void Assault and Leap to quickly and sneakily go over walls. This is done better when you have Evolved Wings

Tip 3: If you are being chased by someone like Tryndamere, jump a wall, let him spin through it, then flash back over. NOTE THIS MAY NOT ALWAYS WORK AS SOME TRYNS RUN FLASH AND YOU MAY JUST DIE AGAIN

Being counter jungled is never a good thing and there are a couple of people in particular who REALLY mess up your day.

Public Enemy Number One
Amumu

There is a reason this little guy has no friends, because he's always in your jungle and with him being in those tissues, he's hard to put down and tears make your wings wet.

Offender Number Two
Warwick

The best duelist in the game is a force to be reckoned with in the jungle, unless you can get the drop on him early. He has a lot more sustain than you and can track you when you are low. I recommend warding your jungle if this guy is on the enemy team and he is jungling as you WILL need help in making this wolf howl in pain.

Offender Number Three, The Nemesis...
Rengar

This one requires a LOT more care when ambushing as he has the advantage of he can track you while he is stealthed. This is why i suggest packing Oracle's Elixer in almost every match. Killing a Sight Ward or Vision Ward is a nice little boost to your income. and will keep you and your jungle hidden from prying eyes. Since rengar excels at fighting by auto attacks, Kha'Zix Requires a more "Hit & Run" Approach.

Battle Log!

Open with Taste Their Fear and Unseen Threat
If he doesn't run away like a wuss, use your Void Assault and move to his side and apply Unseen Threat and Taste Their Fear. Use Void Assault again and run ahead of him to keep up then repeat this process of stealthing and triggering passive until he dies. Dont forget to Leap Over walls and Void Spike to heal up a little bit.

More to come...

No data at the moment....

Most people would tell you to Evolve Claws first. No, you dont want this. Evolve Spike Racks gives you a massive sustain boost as each explosion you are near heals you. So if you only put 1 point into it and evolve it, the base heal of 40 is multiplied by 3 making it a 120HP heal every fed seconds. Which is pretty decent.

Evolve Wings should be done second to close gaps, turret dive and just move around and jump about to make you harder to catch.

Evolve Claws will turn your Taste Their Fear Into an execution move. I recommend evolving this over your ultimate as it really is not needed.

Most games, you want to evolve the following
Evolve Spike Racks
Evolve Wings
Evolve Claws

Evolving Void Assault is the most pointless thing EVER and should only be done if you succeed in "The Hunt Is On" or if your team is rolling really hard and you can afford to use the final point as a Style Point

I have had this happen to me TWICE yesterday.

I have Won once, and Lost another time.

This buff is only available ONCE per game. It usually happens from 40 minutes onwards and by that time, everyone is level 18 or close to it.

Here is what i have discovered from playing as Kha'Zix during this event.
Requirements:
Rengar Possess his Bonetooth Necklace
Rengar and Kha'Zix are level 16 or 18 (unsure which)
40 minutes has elapsed (unless both are doing really well)
Kha'Zix has spent his 3rd evolution point.
The other character must respawn before the event triggers (unsure)

I doubt the event is random, but try and satisfy these requirements first. I am unsure about the "40 minutes has elapsed" Requirement but i havent gotten it any earlier.

Yes this HAS been tested on the live server. i dont play PBE

This section will be for match history images supplied to me so i can post results with this guide.

xX Doubt XxI recieved my 4th evolution point during this match

Please be kind with your voting and i welcome any sort of CONSTRUCTIVE feedback in relation to items and other stuff.

This guide is very much a work in progress. Please try before you vote and more items will be discussed later on and results of my games posted as well.

Ranked Testing IN PROGRESS. Old build failed, updating when i discover more things

13/10/12 - Updated evolutions section to replace Void Assault with Void Spike. Also updated skill order, Item purchases, Summoner spells.