Hello,i m ShockMaster and i play Kennen since season 6. My highest rank was Plat 1,playing only Kennen mid from bronze 1 to plat 1. In this new season I achieved plat 5,and i m gonna catch diamond quickly,maybe more :)
Edit: After a long time, I decided to edit this guide once again for all of you. Now I'm still playing Kennen and I reached Emerald this season and I would like to help you all with all of my new knowledge about him.

Sorcery I use this rune page first for the Damage and CD reduction,which is the most important on Kennen.
Summon Aery,this KeyStone is the best one right there,your poke is important and you can t wait for Electrocute cooldown.
The Ultimate Hat help you a lot with his Slicing Maelstrom cooldown,which is very good
Celerity best one,great combination with Lightning Rush which gives you a good movement speed and ap at teamfights
Scorch is very good with Thundering Shuriken,i usually rush it as last rune
Second Tree
Nimbus Cloak Replaces now the removed The Ultimate Hat Rune. You have to choose this rune, being essential to a speed-driven champion like Kennen,which is very important in teamfights.
Domination These runes gives you a bigger powerspike than the Inspiration runes.
Taste of Blood replaces the old start on Kennen with old runes and Doran Blade,giving you sustain.
Ultimate Hunter is like the old The Ultimate Hat. This rune helps you a lot with CD reduction,depending on how many Takedowns you make.

Your core items on Kennen are Hextech Rocketbelt, Ionian Boots of Lucidity and Shadowflame. If you are playing against hard scaling Ad champs, you can consider buying Zhonya's Hourglass, and if you are playing against lots of Ap champs, buying Banshee's Veil is a solid option.
While you are ahead, buying Mejai's Soulstealer and Rabadon's Deathcap would help you a lot.
If you are playing against healers, you might buy Morellonomicon.

You should max it like this in every game R-Q-W-E

Kennen's abilities add Marks of the Storm to opponents, which last for 6 seconds. The marks are consumed at three stacks, stunning the opponent for 1.25 seconds while restoring 25 Energy. If the same target is stunned more than once within 6 seconds, the stun lasts only 0.5 seconds. This passive is actually super strong, crucial in laning phase, and must be given close attention in order to secure a kill. It's Kennen's only form of stun, and flows really well with his kit, and when combined with Slicing Maelstrom, his ultimate, it basically becomes an area of effect stun.

Cost: 60/55/50/45/40 Energy.Range: 950

Kennen throws a fast moving shuriken towards a location, causing damage and adding a Mark of the Storm to any opponent that it hits.Throws a shuriken that deals 75/115/155/195/235 (+75% Ability Power) magic damage to the first enemy it hits. Thundering Shuriken is a basic ability,try to hit as many as these as you can in lane. If you catch one of Thundering Shuriken,try to use Electrical Surge and if you think you are able to kill enemy use your Lightning Rush to stun the enemy This ability helps you a lot when you are against a heavy hard matchup,to play passive

Cost: 40 Energy Range: 725

Kennen passively deals extra damage and adds a Mark of the Storm to his target every few attacks, and he can activate this ability to damage and add another Mark of the Storm to targets who are already marked. Passive: Every 5 attacks, Kennen deals bonus magic damage equal to 15/20/25/30/35 (+0) (+30% Ability Power) and adds a Mark of the Storm to his target. Active: Sends a surge of electricity through all nearby enemies affected by Mark of the Storm or Slicing Maelstrom, dealing 65/95/125/155/185 (+55% Ability Power) magic damage. Electrical Surge passive helps you a lot with a mark of your passive,and for some nice damage.In lane it's just used after hitting a Thundering Shuriken for some added damage, unless you're trying to stun to get a kill.In teamfight you must use this ability in combination with Slicing Maelstrom

Range=200 Cost:100/95/90/85/80 Energy

Kennen Kennen morphs into a lightning form, enabling him to pass through units. Each enemy unit he touches takes damage and receives a Mark of the Storm. Kennen doubles his base movement speed and ignores unit collision for 2 seconds, dealing 85/125/165/205/245 (+80% Ability Power) magic damage to any enemy he passes through. Additionally, Kennen will gain 10/20/30/40/50 Armor and Magic Resist for 4 seconds.Kennen gains 40 Energy the first time he passes through an enemy.Lightning Rush deals half damage to minions. Lightning Rush This ability, when used correctly,is very good. It's a much needed mobility ability and makes Kennen pretty hard to gank or get caught while also having the ability to be used for wave-clearing; You can just dash through all the minions, and then use Electrical Surge on them all.

Cost: No Cost,Range: 550

Kennen summons a storm that strikes at nearby enemy champions for magical damage. Summons a magical storm for 3 seconds that deals 40/75/110 (+20% Ability Power) magic damage to all enemies near Kennen every 0.5 seconds. Each maelstrom hit applies Mark of the Storm, up to a maximum of 3.Successive maelstrom hits against the same enemy deal an additional 10% damage for each hit they've already suffered from this storm. Slicing Maelstrom This ult is the key for winning the most of the games,i swear.When i losed a match with Kennen That was because i was a little bit behind with the other champs,or i didn t use my ult when Slicing Maelstrom was on cd This ability is like a circle of death for your enemy. Your stacks of Mark of the Storm applied with Slicing Maelstrom. Since it applies the stacks from Mark of the Storm, when combined with Electrical Surge, or sometimes even just on it's own, it can become a massive area of effect stun. Use your Lightning Rush combined with your Flash and with your Slicing Maelstrom which makes it much easier to get huge ultimates. I usually use Slicing Maelstrom when i have Flash on,cause in this mode you can surprise the enemy. Note Patch 8.9 P.B.E changes,mini rework at Kennen with Electrical Surge and Lightning Rush Electrical Surge gets on pbe a large buff,he gain more Base Damage and more Attack Damage,which possibly makes him a champion who can try a hybrid build. Lightning Rush If Lightning Rush damages an enemy champion, Kennen gets 30/40/50/60/70% Attack Speed for 4 seconds upon existing Lightning Rush. Lightning Rush bonuses no longer remain when Kennen returns at his normal form.

Flash is the first spell for you,great engage spell, also great for escapes. You can usually start a teamfight with E-FLASH+R+Rocketbelt+W+Q
Ignite second choice for an agressive start,I'm using it most of the time as a second spell.
Teleport,use that if you want more map control for your team
Barrier against assasins like Zed, Talon etc

Play Video





Play Video











Play Video

Pros

+ No mana champ
+ Very good at teamfights
+ One of the most fun champ to play with.
+ Great snowball
+ You can easily turn a teamfight to your team's favor.


Cons

- An exotic pick on mid, his waveclear isn't very good.
- You'll get flamed sometimes for picking him at mid,cause he is normally a toplaner,but i prefer to use his snowball power on other lanes,and Midlane is the easiest one
- Squishy champ.
- Hard to engage against enemies with CC.

E on creeps, W, auto, Q, auto, keep doing autos.

Simple combo:Q, 4 th hit on minion,w active,w passive
Skirmish combo: W passive auto, E, Flash W active stun, E(cancel ur e) aa + Q + aa
Ranged stun: W passive+Q+W for a ranged stun
Chase combo: E+Q+W
Retreat combo: W passive+Q+W
Maximum damage combo: E+R+Rocketbelt (Rocketbelt, and then you are using R in MAX 1 sec,biggest impact damage, W+Q+W passive and there you have 2 stun stacks,the enemy can't even move,also you can use ignite for securing if you're not having enough kills yet.

Always roam when there are lots of minions in front of your enemy's turret. By doing that you are increasing the confidence of your team.

Kennen might be one of the funniest champions to play with. He has almost everything you need, and you can climb easily if you play correctly with him.