Pros

+ Good clear speed and sustain
+ Reliable slow with Unseen Threat
+ Huge burst potential on isolated targets (Top and mid are usually alone)
+ Resets with evolved Leap
+ Jukes for days with new evolved Void Assault

You clear fast with isolation and with good sustain due to Void Spike.
Ganks are fairly easy with the slow on your passive and W, and with your Leap.
Taking away Drake and Baron is a breeze with evolved Q (since they are always isolated).
You can pretty much just assassinate the enemy ADC and/or APC/Assassin and then GTFO.



Cons

- Lack of CC
- If you get caught with Leap and Ult down you are dead
- Pink wards will make your escape hard if you run with Ult
- You are almost as squishy as the targets you want to get to

You are an assassin act as such.
You can't go head first into fights, careful planning and flanking will win your battles.
You don't have much health and resistances, you can't allow yourself to get caught.
You should wait for your teammates to engage in teamfights, because you can use your missing health damage on your evolved Taste Their Fear better then.

I take 21/9/0 for Kha'Zix since he is an assassin jungler. You are melee, so you can make a good use out of Double-Edged Sword . CDR from Sorcery is also useful. I take Spell Weaving to increase the damage on Taste Their Fear. Executioner allows you to blow up enemies bellow 50% health. I take the 6% APEN from Devastating Strikes to murder tanks faster. 9 points in deffense for some sustain.

Greater Quintessence of Attack Damage: AD or MS. I prefer AD.
Greater Mark of Attack Damage: Even more AD, good for clearing. Greater Seal of Armor: Yeah, jungle hits hard. Protection is required.
Cooldown as cooldown, always usefull

Flash: If you don't have your Ult nor your Leap it will save your life. Or might cost your enemy's double buff.




Smite: It is not impossible to jungle without Smite but I don't recommend it. Securing buffs, Drake and Baron is easier this way.

Teamfighting when you are ahead

If your team is ahead then you can pick your fights. One little mistake from the enemy can result in an Ace and a victory. So you should try and force them to make a mistake. Flanking, getting behind the enemy and having a position advantage on your side is key. Two simple reasons: First, flanking means that you are not together with your team, just near them. So you are closer to the enemy. When a teamfight breaks out you will be close to the enemy ADC or APC/Assassin, that means that the bruisers and tanks fighting in the front line won't be able to stop you. Second, if a teamfight breaks out, you can be sure, that the enemy will use almost all of the hard CC they got at the very beginning of the fight. You don't want to be in the fray when your team gets Amumu ulted combined with Orianna's Command: Shockwave.

Teamfights when behind

It's almost the same as previously, however you have to be careful with getting near the enemy, because your team won't be able to follow up, if you get caught.

You don't have combos that you can pull off often, but when you go in you should go in as hard as you can. Use everything you got.
Full assassination combo with Leaping onto the enemy: Smite!! Leap --> While in the air use Ravenous Hydra --> You can use Taste Their Fear right before you land --> AutoAttack --> Void Spike --> Void Assault. Now, a little pause. You have 2 second to decide what to do with your life next. You got Unseen Threat from using Void Assault and Taste Their Fear will be up soon. If you decide you can go for the kill with that AA and Q and still get away, you will have 2 stack of your ult to wreak havoc on the enemy. However if it didn't deal as much damage, you still did your job well. The enemy carry should be screaming and running away from you, the moment you appeared. That means that the carry is running away from the teamfight. Win. On the other hand... If the enemy collapses on you and the carry is not shivering from fear and your Leap is down because you engaged with it, then you just set up a 4v5 for your team. Lose.

Kha'Zix is a high mobility, high damage Assassin, who is best at picking of enemies one by one. The missing health damage on evolved Taste Their Fear got nerfed recently, still deals a lot of damage, but Riot made it up by the awesome buffs to evolved Void Assault. He is very fun to play due to his predatory play style and resets with evolved Leap.

This is all that I could share with you guys. I hope you like my (first) guide and I would realy appreciate if you could send me some feedback. For example if you downvote please tell me what made you downvote, because if you don't, then I can't improve my guide. So really, tell me what you didn't like. If you downvote and than tell me nothing I cannot change anything.