Hello, I am an average or I guess above average Kennen player just writing a guide to help the community play against him and play as him. Kennen is one of the three ninjas obviously, but he is the caster of the three. He is a unique character in many ways, he uses energy instead of mana, he has no hard cc ability he depends on his passive, and hes pretty fast paced for a caster. In this guide I will explain his pros and cons, his downfalls, the key to success, the teamwork needed, the explanation on everything.

Pros
- He is a caster with limitless combinations to harass and potentially the caster with the most cc.
- His range is far for all his spells except his rush and you can say his ult I guess.( Only problem I had with the range is someone flashes out or I'm not fast enough to keep them in it.
-He has a lot of damage from his burst, and a good amount of Damage Per Min if your harass is good.
- He is a very fast and fun caster. *Adrenaline might be felt*
Cons
- He is not the squishiest casters but he cannot take as much harassment as he dishes out.
- End game unless your fed, your team only uses you for your crazy ability to stun their whole team.
- Most of your kills should be from 1 v 1 or from a small team fight.

Runes are simple and easily understood, all casters need AP to function correctly, the magic pen helps with overall damage, the health quints can be replaced since the nerf kind of killed them. In my opinion still viable, saves my but multiple times with 20 hp left.

Masteries for the 1st version.
9/19/2 This is a very tough ninja with team oriented spells.
The 9 is for the AP and the obvious magic pen.
The 19 is just the extra defense to stay in the lane as long as possible.
The 2 in utility is to help your summoner spells Teleport and Ghost.
The 2nd is more aggressive even though you have less survivability compared to the 1st one.
The 21 in Utility helps with the movement speed, cool down, and experience with a touch of ghost mastery. The rest is to lead up to the 15% Summoner spell reduction.

Teleport, Very very useful when trying to get back to a lane, stop a push, back door, anything really that requires you to go long distances.
Ghost, EVERYONE I know uses it, its just to diverse, the amount of possibilities are endless seeing that the game is different every time.
Really both don't need any explanations, this version focuses on teamwork and lane holding/pushing more than the other version.
The flash for the 2nd version is to flash in and Ult or flash to save your life.

Items are mostly from recommended just because Riot actually made the items that go with him are very synergistic.
Doran shield, just the little extra survivability, this items works on every champion. The ring, he doesnt even use mana, the blade, really? This is a caster version not a hybrid or DPS. So I think staying in the lane, able to take harassment well, and just to stop DPS from hitting you a little.
Rush that Rylais! It is his main item, it is basically a constant slow for him seeing his cool downs are moderate for a caster. The AP for the damage of course, the HP just for the survivability he WILL need seeing his ult requires him to hit as many people as possible.
The boots, does not need to be explained, but it can be replaced with CDR boots, I've never tried it tho.
Then go for Abyssal Scepter or Rabadon's Deathcap.
The AoE MR Debuff really helps when his ult is activated. The rabadons? Who DOESNT Want more AP?
If your getting destroyed while your ulting in, rush that Hourglass ASAP, it will save your life when jumping into that team.
The Will of the Ancients, another survivable item, since Kennen's damage is constant or a burst, the spell vamp will be helpful.

You probably noticed the skill order is very odd, Let me explain.
I tried this and It worked out fine for everygame I play >_> but my play style is very different from most people I guess.
First rush your Q to level 3 before you get your ult, why? Thats your highest damaging harassment and last hitting tool and you wont need it after so max it last.
Then max Electric Pulse, after you get your ult, this is VERY Helpful, the damage is pretty sick and its another mark or a stun without the risk of missing the skillshot. It should be maxed around 12-13 If I remember correctly.
Then max your rush, end game, your main role is to literally rush in and pop your ult and hope you don't fall first, because your ult is 3/4s your damage if your hitting all 5 of them, but then you can't forget your Q, it is a NUKE almost.
Ult should always be leveled when available.

Alright this is potentially half your early game until level 11, why? Your not going to have another chance like this during the rest of the game, so make it worth it and get rich!
Always last hit, auto attacking might be helpful if pushing but last hitting should be your number 1 priority because harassment is around level 2-4 where you can hit 100-200 damage per burst.
If the minion is low on hp, right click.
If medium hp, right click followed by a Q to finish it off.
You can get 2 last hits since your auto attack and Q have no time in between them.
Late game farming is simple, do you think you have enough AP?
Well lighting rush into the line or row of minions and electric pulse immediately to get the last hits, if not Q the nearest one and auto attack the rest.
Repeat all the steps for last hitting.

The unique thing about this build is well... I honestly do not know, I am just a Kennen player that wants to get more Kennens in this world! Hes pretty OP I guess after the buff that adds Marks for every strike from his ult, instead of 1 max.
But seriously Ill explain what you need to do with the spells.
Common Kennen harass
Q then W and Rush in with E if there low on hp or just scared of you.
Or
You hit something 3 times and then run up and hit them with the 4th auto attack and then W and Q if their in range and in the way, if missed and there close enough rush in with E.
*Important note, always lead your Q into them or aim your Q when their stunned, just get W up rush in and W to stun and hit with Q to have a sure hit.
*The way I play Kennen is very odd, how I use his ult is very different.
*Initiations, I go in first, but in 1 v 1s Its a whole different playing style.
You should take them down to half or so assuming your at mid. After that and all your CDs are down and you have at least 1 mark of storm on them to ensure a stun. Pop your ult and the 3 hits should leave them stunned and with 1 or 2 marks of storm. There you W and or Q and make sure you have the auto attack with the mark ready.

You are a good team champion. Your role, mass CC and damage.
Your role endgame unfortunately, is to run in ult and run out, but if you think you won't die, stay and just get as many stunned. Other than that he can be used to clean up if late to a fight, ghost in and ult the remaining few and finish them off.

Thank you if you read the whole guide, it wasn't very long :D.
Here are my main points.
1. He is a very good caster but he is expensive.
2. You have the most cc on a caster possible I guess.
3. The damage is insane, harass or with killing intentions.
4. Hes fun, fast paced, and gives me a few adrenaline rushes when in a tight situation xD.
5. Hes a good team player and a better 1 v 1.
Good luck and own all.