Welcome to my first build!
This build is about my very favorite champion in the League of Legends: Kennen.
There are a couple of reasons why I just love this little guy: well first of all, he can take multiple enemies at once, he can stun-lock enemy champions with no problem, he can drive enemy champions CRAZY with his constant harassing techniques and much, much more...
Before anything I just want to make one thing clear: if you want to troll something YOU ARE ON THE WRONG PLACE, this is a build which you should try before spitting on it and giving me some absolutely stupid and worthless comments, I do not mind the down-votes as long as it is followed by some constructive critics, good votes are always welcome of course.

Pros:
Constant and multiple harass techniques.
Huge burst damage.
Can interrupt enemy champion channels such as Nunu's ultimate, Katarina's ultimate, Warwick's ultimate...
He can stun-lock enemy champions.
Since recently buffed, he can now carry.
He is a ninja!


Cons:
Extremely squishy.
Focused quite often because of his HUGE damage output.
Takes a while to master.

I use the runes showed up there and now I will explain why:

Marks: As you can see I use Greater Mark of Magic Penetration. Not much to say about them, they will help you early game and can work well late game but nothing too much.
These are the only marks I every tried using for Kennen since they are good and everyone uses them.

Seals: I love using Greater Seal of Scaling Ability Power because they are just awesome, well you will feel the impact on your ability power early game but they make up for it after LV6.
There are some other runes you could be using depending on your play-style:
Greater Seal of Vitality <-- I have been using those for quite a while but I figured I don't need them actually and I like to focus on the damage output since you get enough health and resistances from your items. If you ask me 2200 health is quite good on a squishy ability power champion.
Greater Seal of Ability Power <-- These I don't use since I focus on late-game team-fights and not early-game ganking, I suppose these are quite good if you want to end game quickly which will usually not work in ranked games.

Glyphs: As you can see up there I am using Greater Glyph of Scaling Ability Power the description is the same as with seals and it really does not make sense to repeat something one hundred times over and over again.
You can also use:
Greater Glyph of Ability Power <-- As said earlier I focus on late game so I do not prefer using these but I suppose they are quite good, since they work well on other AP champions...

Quintessences: As you can see I use Greater Quintessence of Ability Power <-- They really help in early game, 15 extra AP is really great since you don't take amplifying tome or doran's ring...
Greater Quintessence of Health <-- I have been using these for quite a while, awesome runes indeed, great for early game, but if you take Doran's Shield as first item you don't really need them, sure extra hp is nice but you have enough even without them...
Greater Quintessence of Scaling Ability Power <-- These are the only ''per level'' runes I do not prefer using since they become better then flat AP runes on LV 12 which is too late if you ask me, sure I do focus on late game but these just aren't worth the trouble.

These are somewhat usual Kennen masteries setup, only thing is I don't take Nimbleness , the reason for that is because I have low respect for dodge, in my opinion this just isn't a good stat for AP nuker, really how often does 2% dodge chance help you against enemy champions, that is right, it does not. The only moment when this talent would be useful is when chasing someone while the enemy minions are attacking you and you somehow manage to proc your 2% dodge stat for the low movement speed increase effect... Really... Man... 2%... Really...
You can also go Burning Embers by sacrificing your Tenacity but first ask yourself: How often do I actually engage one on one without having my Ignite ready... I will let you decide for yourself, is it really worth it.

As you can see I use Flash and Ignite.
Ignite will cover the little bit of damage you are missing early game, while in late game it will mostly be used to severely reduce enemy healing spells such as Mundo's ultimate and Olaf's Tough It Out.
Flash is my favorite summoner spell.
It has saved me countless number of times from ganks. In combination with Lightning Rush it can be used to escape from team fights if you get to low on health. Not to say how awesome it can be for running from enemies in the jungle since Flash enables you to pass through every wall on Summoners Rift.

Summoner Spells to consider:

Ghost <-- This one I do not use on Kennen since his Lightning Rush gives him all the speed he needs. I suppose it can be used but I do not prefer using it while playing Kennen.
Exhaust <-- You will see this really rare on Ability Power nukers since it should be used by Attack Damage Carries and Tanks instead.
Heal <-- Seen a couple of Kennens with this but you probably won't see a Kennen in ranked using this summoner spell and not to mention this spell should be used by supports instead of nukers.
Teleport <-- This is quite good Summoner Spell and you could use it if you have to go base more often (so you can return to your lane faster) but I don't prefer using it because in my opinion it should be used by AD farmers and backdoor champions such as Sivir or by champions that like to multiple their abilities such as Shen and Twisted Fate.

I decided not to waste time on explaining why not to take some Summoner Spells such as Revive and Clarity because I think it is quite clear why people don't use it.

Doran's Shield Like most Kennens I use this as my starting item.
I have seen some Kennens using Amplifying Tome and Health Potion as starting items but I don't prefer those since I like the stats that Doran's Shield gives; that Health bonus comes in handy, Armor works well while creeps are hitting you when you are initiating a fight at mid, Health Regeneration that it provides is just awesome and is always active unlike potion which you can use only once and after that you will have to deal with really low health regeneration which will make you go to base more often and lose experience which my lead to being absolutely useless in team-fights because you will be 2 levels lower then everyone else.

Needlessly Large Rod is the first item I buy when I go back from lane. With this item you have ton of ability power early game as well as mid and even through late game.

Boots are the second item you should buy. You need them, they are good, and really necessary...

Rabadon's Deathcap. Now this item i just love. Now you will find out why do I rush it so fast:
Number 1: Once you make it you can kill the caster creeps with your simple spell combo for killing creeps ( Lightning Rush and Electrical Surge) and if done early enough even the little fighter minions,this will make you farm lots and lots of money in a short amount of time.
Number 2: Your huge damage output. You will be surprised by the damage you deal with your simple spell combination and how you can devour enemy squishy champions and AD carries such as Caitlyn, Ashe...
Number 3: This is the most powerful AP item in the game. Remember that it transfers 30% of your ability power into even more ability power which makes it just AWESOME!
Trust me you should try rushing it as your first item and you will be surprised how good it is.

Mercury's Treads I make these almost always on Kennen. I just love the disable duration reduction that they provide, although they give Magic Resist which should be used on a tank instead of AP nuker that disable reduction comes in really handy against annoying crowd controlling champions such as Galio, Rammus, Shen, Taric... Here you could use Sorcerer's Shoes as well but as said earlier I prefer the disable duration reduction over a little bit of more magic penetration.

Hextech Revolver Why this item? I believe it is quite obvious, it is one of the rare items that give spell vamp which works awesome on Kennen. Now here is one handy move you can make with spell vamp; If you are low on health and someone like Mordekaiser uses his ulti on you throw Thundering Shuriken on wolves or wraith packs in the jungle, it will give you ~ 60-70 health with only Rabadon's and Hextech revolver, you can also run in the wolves and wraiths with Lightning Rush and use you Electrical Surge for some super healing.

Rylai's Crystal Scepter I make this item right after Hextech Revolver mainly because of the health it grants (after you make this item you will have 2200+ health which is really awesome), it gives a little bit of bonus ability power but nothing too much and finally the slowing effect, I just love this part of the item, it has saved me countless number of times when escaping from some nasty champs like Tryndamere and such... (generally the ones that can 2-3 shot you and the tanks no matter what).

Zhonya's Hourglass This is just really awesome item, it grants quite a lot of ability power, that armor isn't too much and isn't a stat that ability power nuker needs. It's ''use'' effect is awesome since you can use your ulti and use this item, your ulti will keep spiking at people and doing damage, it can also be used in huge team-fights while you are being focused, if you use it in the right moment it can also be used to avoid annoying ultis that would usually kill you such as Caitlyn's ulti, Karthus's ulti, Nunu's ulti...

Void Staff is what you should buy right after you sell your Doran's Shield, this item is just awesome, it devastates the enemy tanks and tanky champions that hate overfed AP nukers/carries, you have 55% magic penetration if you count the 15%magic pen from masteries (+ some flat from your runes)... It is just awesome and lifts up your damage output A LOT, some people think this should be rushed faster, I agree it can be bought early if they don't have someone that does a lot of damage and focuses you...

Abyssal Mask can work as well if they have a really fed AP carries who focus you (though you should be able to avoid such problems with Zhonya's Hourglass use effect) it gives a little bit Magic Penetration which is not the main reason why this item is bought but it comes in handy.

Mejai's Soulstealer - I will dedicate a whole chapter to this item to explain why do I sometimes do it and sometimes don't.

First of all this item is playing like fire... If used correctly it can bring ashes and destruction to everything around it, but if used incorrectly it will bring ashes and it will destruction but not to everything around it, but to YOU.

When playing ranked (and sometimes normals also) it is a huge risk to take this item because as soon as someone sees you made this item you will be getting focused and ganked more often.
Why? Because this is the highest Ability Power item in the game, at 20 stacks it gives more Ability Power then Rabadon's Deathcap and that is too much for the enemy team to handle.
So I don't prefer using it since it is quite irritating to get stunned, suppressed, feared, knocked back, pulled back in, and killed before you actually use any of your spells...

However if you feel confident enough buy this item, it is really awesome, as said, it gives more Ability Power then Rabadon's Deathcap + that cooldown reduction is really great, BUT be careful, everyone in the enemy team will hate you and will want to see your head on a spear...

Conclusion: This item is good if used correctly and if used incorrectly you will suck.

Thundering Shuriken -I max this spell first because it does HUGE damage if you can aim with it... Since I have been a League of Legends player for a while, I can aim easily and hit with a skill shot even between creeps. This spell hurts a lot and if you have rylai's slows as well which is awesome...

Electrical Surge -I max this second because it works better then lightning rush since it is guaranteed damage, it works awesome for aoe and it is essential for your stun, a great spell but thundering shuriken does more damage and is used for last hitting early in the game.

Lightning Rush -I mark this spell the last since it requires a lot of energy and you have to go through the enemy champions to damage them which makes it easily dodgeable and will often make you overextend. This is a spell that is really under-respected by Kennen players. This is actually and awesome spell that will often save you when escaping from enemy champions. Also you always must read carefully what does the spell do, you can see it gives small amounts of armor and magic resist, this can be used quite well when you know you are going to get shot by some long-range executing spell such as Karthus's ulti and Caitlyn's ulti. (This spell won't protect you from much damage and should not be spammed since it wastes a lot of energy, the bonuses aren't much either but Movement Speed Bonus + Armor and Magic Resist is not something to throw away.

Slicing Maelstrom -This is your ultimate so take it whenever you can (just like on every other champion in the game). Your ultimate is really awesome, it spikes at 3 nearby enemy champions dealing HUGE damage and stunning them. This is just a devouring spell and is a must-use in team fights. If you don't have your ulti available then better don't engage at all. This spell is kind of a double-edged sword... It is powerful and it does stun but you have to go inside the crowd which can get you focused and even killed. You should also remember that even while you are in ''stasis'' effect from Zhonya's Hourglass your ulti will keep doing damage.

In early game you should focus on the last hitting a lot since you need a lot of gold for your Needlessly Large Rod, don't push the creeps, just auto attack them...
THIS ONE IS PRETTY IMPORTANT: If you get stuck under the turret by the enemy champion you can still last hit without a problem, the turret attacks one creep at a time, if it attacks the fighter creeps let the turret hit them twice and they will have around 50 health less and then just kill them...For the caster creeps you use a different approach, if the turret attacks them you will not be able to finish them with your auto attack, you will be able to kill them with thundering shuriken though... Listen what you will do with them, auto attack them once BEFORE the turret hits them, let the turret hit them and then auto attack again. This probably will take some practice but eventually it will become completely normal.
After needlessly large rod creeping will go extremely easy since you can kill the caster minions with your simple spell combination.
With Kennen you shouldn't really go to the jungle at all... You don't really need the blue or the red buff so better let someone else who actually needs it take it.
You could go to jungle to kill wraiths, wolves and golems but it isn't a must.
You can solo the dragon but I recommend doing it only after you have Hextech Revolver and Rylai's Crystal Scepter but watch out for ganks while killing it since you can't handle enemy champions and dragon attacking you, in that type of situation just try running away instead of fighting since it is safer and you have more chance of surviving... Even if you manage to kill the enemy champion the dragon will keep attacking you and doing some pretty nasty damage so be careful not to die from that.

In this section I will tell what do I focus on and what do I do in certain parts of the game.

Early game: In this part of the game you should mainly be focusing on creeping (so you can buy your Needlessly Large Rod on time). Sure it is good to harass the enemy early in the game and you should do so, but remember to use your auto attack only to last hit the creeps and not auto attack them all the time which will result in bringing the fight by the enemy tower. It would be excellent to have around 100 creeps by the 15th min. It is also good to focus harassing before First Blood is done (so you can take it), but after it you should focus on creeping more.

Mid Game: By this time you should have your Rabadon's Deathcap, Mercury's Treads and if fed enough Hextech Revolver. With these items you will not need to go to base that often (if you fall really low just shoot your Thundering Shuriken and Electrical Surge at the wraiths and wolves packs in the jungle) which will result in being able to help when some lane is getting ganked and being prepared for team-fights. In this part of the game you should focus on harassing and ganking, as well as on counter-ganking (when some lane gets ganked most of the enemy champions try to push at low health which is extremely stupid and just perfect for you).

Late Game: In this part of the game you should have almost full build, the game will mostly be focused to team-fights on mid and near Baron Nashor. Remember that you should not engage team-fights since you are not the tank. It is good to tell your team when you have your ult available (since it is good to be actually useful in team-fights).

Late, Late Game: This is the part of the game where everyone has full item builds. You should grab your elixirs and head for mid where everyone will be fighting at this part of the game. Most probably there will be one or two team-fights left because the respawn timers will be huge for both teams. Now you will take a LOT of damage and probably eventually die in team fights but remember to ALWAYS use your Zhonya's Hourglass when you use your ulti (if you don't use it you will just die and be useless) in team-fights, it can sometimes keep you alive long enough for your team to kill the enemy team which will often result in your team winning the game. In most of the games it will not reach this phase of battle (it takes longer than 1 hour I think), but if it does don't lose focus and you have a chance.

Kennen has multiple harrasing techniques and I am going to explain some of them.

1. The common Thundering Shuriken and Electrical Surge combination, works quite well but your opponent will start hiding behind creeps once he sees the damage you do while harrasing.

Once your opponent starts hiding behind creeps it is time for the second type.

2. Auto attack the creeps until you stack enough attacks for passive of Electrical Surge to proc. Once you have it just auto attack the enemy champion, and use Electrical Surge since he will have Mark of the Storm on him and quickly back out since creeps will probably be attacking you.

3. This is the nastiest and the most powerful harrasing technique and can also be used to initiate. Use your Lightning Rush to move through creeps and apply a initial Mark of the Storm on the target. Next use your Electrical Surge. Now your opponent will probably commit a terrible mistake... He will start running... Once he is out of his minion crowd you have a clear shot with Lightning Shuriken so don't waste it. Your opponent will be stunned now and you can auto-attack him for some additional damage.

When you think your opponent is low enough go for the kill. There are multiple ways to initiate and I am going to explain some of them.

1. Do exactly the same as in Harassing technique no2 just use your Ignite and take a risk with your Thundering Shuriken to have it available again as soon as possible. It is also great to stack passive from Electrical Surge so you can land an additional Mark of the Storm on your target after the stun (if he manages to live that long...

2. You can use your Lightning Rush and Slicing Maelstrom really fast and before your opponent even notices something Flash on his head, from here on just use your common spell combo with Ignite... He will be really scared and will probably die. If he uses his Flash remember that you are faster then him because of your Lightning Rush and you will be able to catch him with the edge of your ulti what is enough for stunning him... Feel free to keep hunting him if you aren't to close to his turret. But watch out if you overextend enemy jungler can come to gank you. If the enemy uses Flash and Ghost just give up and don't waste any more abilities, remember if he did that he wasted all he had to run away from you so you can feel more confident and engage again.

When you attack an enemy champion in an attempt to kill them (using your ult) you should look carefully not to waste your electrical surge since you will not do enough damage and fail at killing him...

Kennen is a great champion and if played correctly you can devastate enemy teams and even win 3 on 1 situations (that is if you are really fed).
This build will ensure success with Kennen but remember if you fail at first it may be because you are untrained or you have a different play-style.
For me this build works perfect and in the past few weeks I haven't lost a single game with Kennen (normal and ranked).
Since recently buffed Kennen can now be a good AP carry so use your power well...


That's all folks! I hope you liked it, please don't troll and don't judge before you try it out.
The reason I put ''requires comment to vote'' is to prevent trolling and down-voting with no actual reason.
If it works well please vote, as I said at the beginning i don't mind the down-votes as long as their are followed by some useful and constructive comments.

25.3.2011. <-- Made the build.

1.4.2011. <-- Published the build after some grammatic corrections and last minute changes.

6.4.2011. <-- Made the Mejai's Soulstealer section.

27.4.2011. <-- Made the Play Style section and added some color to Quintessence part of the Runes chapter.

7.7.2011. <-- Yay, reached 100 000 views!!! Oh right!!

23.8.2011. <-- Updated the build since he got buffed recently and a lot of items got changed (price and the effects), He CAN BE A CARRY now and you should use it...