So basically this is my first time making a build. I just recently bought Kennen and his kick-*** karate skin. So far I tried Hugenjpana's guide and I kind of died way too fast. So... I made a more tanky version and I seem to have won 13 straight games and only dying once or not even dying at all. I find Kennen to be the easiest character to use because he has....

1. Good range for harrassing and last-hitting minions and low cooldown on his Thundering Shuriken (Q)

2. Good range and good farming capabilities on his Electrical Surge (W)

3. His Lightning Rush (E) is like a mini ghost (Summoner Spell) that deals damage and applies his passive.

4. His ultimate Slicing Maelstrom (R) is a huge AOE stun which is very useful in teamfights.
All these characteristics are what makes Kennen a beast. The only thing he lacks is Health (HP). Since Kennen's ultimate allows him the best initiator, we need survivability or you'll die..... Which is why I created this build :D

Runes...

-Marks: Magic Pen
Why? Well Magic Penetration is what allows you to do such good damage. The more we obtain the more we'll hard on those people who make Force of Nature, Banshee's Veil, or Abysmal Sceptor.

-Seals: Health per Level
Why? Wow this gives you a whopping 175 health. That's a pretty big chunk which allows more survivability.

-Glyphs: Ability Power per Level
Why? Well they give you a pretty good amount of AP at 18 and the AP evens out with the Flat runes at level 6 anyways. So might as well take the per level runes.

-Quintessences: Flat Ability Power or Flat Health
Why? Well... Honestly, this is debatable.. if you aren't good enough at zoning your opponent then you should go for Flat Health. If you are an experienced player who is good at zoning and dodging skillshots. You should probably go for the Flat AP runes.

Why 9/21/0 not 21/0/9 nor 0/21/9 nor 0/0/30 nor 30/0/0....

Well first of all in the..

Offense Tree:

-Archmage's Savvy: Increases AP per level scaling. Very Nice :D 3 points in here please.

-Deadliness: Well this will receive 1 point because it's definitely not going to Plentiful
Bounty or Cripple. Also if you crit while you throw that shuriken then it just means more damage. :D

-Sorcery: WOW! It reduces cooldown for free :D That's just beautiful.. 4 points in here please.

-Archaic Knowledge: WTF? 15% Magic Penetration for FREE?! Yeah this mastery is sexy. If you don't put a point in here then you should get your head checked...

-Don't get anything past Archaic Knowledge because the tree will start focusing on Attack Damage (AD). Which is irrelevant to this build.

Defense Tree:

-Hardiness: Hmm more armor.. not much, but it's still armor. 3 points please.

-Resistance: Hmm more Magic Defense.. only 6, but it's Magic Defense. 3 points here too please.

-Evasion: Wow once again FREE dodge.. This game is so awesome! :D 4 points please.

-Strength Of Spirit: Nice!! Increases Health Regeneration for a % of your max Mana. 0 POINTS!!! If you don't know why then quit this character immediately!!(Hint: He uses energy :D)

-Harden Skin: Woah it blocks physical damage.. Pretty nice 3 points please.

-Defensive Mastery: Uhm no... Just no..

-Nimbleness: This could also be considered alright if you had decent dodge, but since we aren't focusing dodge lets leave this at 0.

-Veteran's Scars: Woah this gives good Health yeah that's sexy! 4 freaking points please.

-Ardor: Uhm we don't care about the Attack Speed that much, but holy ****!! Increases your ability power by 4%!! Lets go shove 3 points in there!!

-Tenacity: WTF? Decreases all damage dealt to you by 4%? Ok this is BS when coupled with the 20 Leviathan stacks :D 1 pointo please.

Utility Tree:

-Well lets just say there are 3 masteries in there that are totally useless to Kennen (4 if you add that useless of a skill, Clarity for Kenenn). So lets just forget about this tree lol!

-Doran's Shield: Woah this seems like the best item for Kennen to start with because... it gives 3 critical attributes we like. 1.Health 2. Health Regen 3. Armor

-Sorceror's Boots: Well it gives Magic Penetration... And we like to do good damage :D

-Leviathan: Wow it gives amazing health when you have 9 or 10 stacks and superb Health at 20 stacks. But wait there's more... It reduces all damage dealt to Kennen by 15%!!! WTF? Yeah this item coupled with Tenacity is just OMG!! WTF!! Very good for tower diving and crazy team fights!

-Rylai's Crystal Sceptor: Wow this gives 3 things we want.. 1. Health 2. AP 3. Slow. Well this item is just sexy also.. you get some awesome health with good AP and get to slow the opponent down. Just deadly..

-Banshee's Veil: Well this blocks 1 skill. Meaning it can block 1 CC Skill yay! This item is amazing because when you need to go in the team fight with your ultimate you don't scammed by that 1 Sion or Kassidin who happens to do their silence or stun. Pretty nice!!

-Zhonya's Hourglass: Ok this item is awesome because on top of the fact that you are freaking hard to kill.. You get a few seconds of invincibility... Yeah this item is BS.. You this when you engage the teamfight. That way when they throw all their ults on you or whatever you just press 1,2,3, or whatever you set your Hourglass on and just sit as you laugh at them staring at your gold body, while teammates come annihilate them.

-Hogwarts Cap: I mean Rabbadon's Death Cap.. This thing gives 150 AP!?! + it increases your AP by 30%?! yeah this item is BS! Definitely get it if the game lasts that long.

Teleport: Well why Teleport? If one of your teammates gets in trouble or a turret is just getting wrecked by minions or a champion and no one else is there. Yeah you just press D or F and you're there.. Very useful!!

Ghost:It's good for chasing and running. Chasing an opponent with Ghost and Lightning Rush is just amazing. You get stupid amount of speed and you WILL catch them.

Thundering Shuriken: Use this to always last hit the minion because it is fast and has amazing range.

Lightning Rush + Electrical Surge: Basically, when you get a certain amount of AP (300+) you will be able to just Lightning Rush through all the minions and end their lives with Electrical Surge in an awesome 2 Hit combo. Both Lightning Rush and Electrical Surge can hit an infinite amount of minions or champions so try and hit as many minions as you can with Lightning Rush before you Electrical Surge.

Slicing Maelstrom: Don't ever use this to farm or there will be a huge fist that will eject from your monitor into your face. :)

So in conclusion... I hope somebody tries this build out and comment or rate it. XD If you want to add any other alternatives to items or runes or masteries please do comment and we can argue about it :D hahahaha