THIS IS NOT AN IN DEPTH GUIDE, THIS IS A BUILD AND AN EXPLANATION TO THE BUILD, AS WELL AS TIPS FOR PLAYING KENNEN. I USE THIS BUILD ALL THE TIME AND HAVE YET TO LOSE WITH IT. I DID NOT INCLUDE THE HOURGLASS BECAUSE IT OFFERS NO MAGIC PEN, NO SPELL VAMP, AND I PERSONALLY DO NOT FIND IT USEFUL. IF YOU WANT TO USE IT, BY ALL MEANS USE IT. I'VE BEATEN OTHER KENNENS THAT USE THE HOURGLASS WITH THIS BUILD. I DON'T MAKE GUIDES VERY OFTEN, NOR DO I KNOW HOW TO DO THE FANCY EDITING AND ****. THIS TOOK ME A WHILE TO DO, DON'T JUDGE IT BASED ON HOW IT LOOKS, JUDGE IT ON HOW WELL IT WORKS.

First and foremost, thank you for checking out my guide. I've been playing league for just over a year now, and I own well over 60% of the champions in this game. Over the time of my playing, I have spent many hours (and dollars) into this game. After playing champs like Pantheon, Gangplank, and Varus, which where very reliable and had very good CC/ harassment, I thought I had found my niche in the top lane. Then the Season 3 Update happened. I quickly found that my Runes and Masteries no longer synergized how i needed them to. And with the removal of the Force of Nature, Madrid Blood Razor, and The Leviathan, it heavily dampened many of my Off-tank/ DPS builds. Saddened, I looked into playing a different champ. This champ was Kennen, and I instantly fell in love. I have since made Kennen my main. Kennen works amazingly Top Lane, but he can very easily work bottom or made lane. His abilities allow for you to initiate fights and then stun the whole team when you run low on health. Lightning rush + thundering shuriken combo has last hit many champs who flashed towards their towers, hoping to get away.

Now that you have an idea of what you can do with Kennan, let's move on to how you can leave your enemies feeling Thunder Struck...

Pro's:
-All of his abilities work together, as long as you time them properly.
-High energy regeneration allows for easy harrassment of mana-hungry champs and carry's, even when soloing.
-His passive is pretty much a free exhaust, and his E is a free ghost, making him excellent in team fights, chases, ganks, escapes, farming... you name it.
-Q allows for easy last hits, kiting/ poking, and can hit enemies who hug their turrets
-Can be built a variety of ways, including DPS or AP burst, allowing for a number of AP or AD builds.
-Amazing CC

Con's:
-Kennen's Ult randomly strikes up to 12 times and can only stun champions once, meaning that this should only be used to initiate team fights or take out champions 1v1. Also, this ONLY AFFECTS CHAMPIONS, so if you find yourself swarmed by enemy minions/ tibbers/ what have you, this will do nothing to them.
-Kennan uses energy, limiting the number of AP items useful on him (i.e. Archangel and unholy chalice are no-go's). This also means that unless you have runes, you're stuck with the standard energy regen, and with Kennen's Cool Down getting so low as you progress on, it's very easy to mess up a combo because you're out of energy.
-Kennan's W and E only deal half damage to minions, making him unreliable in the jungle. However, he makes up for this by how well he can farm lanes/ the high damage he inflicts to enemies.
-While in ball form from his E, you can not basic attack. You can also be stunned/ silenced/ affected by CC and Disables while in ball form. While you do gain some bonus defensive stats and movement speed, it's very easy to over shoot the target and accidently dive a turret/ get stunned while trying to run away. Be aware of your energy and combo your abilities accordingly.

If you can't already tell, this build is designed to deal the most amount of damage, not through having huge amounts of AP, but by dealing "true damage" with the spells (or very close to it).

If you follow this build, you'll have the following:
30 Magic penetration from your items
11.4 Magic penetration from Runes
35% magic penetration from items
8% magic penetration from masteries (40% is the maximum)

and if you can get an Abyssal Scepter going (I usually take it when there are casters stronger than myself, but if you ask the tank/ support, usually they'll get one) enemies lose an additional 20 Magic resistance.

lets's put this in perspective:
say you run across an enemy champion with 100 magic resist.

Abyssal Scepter's effect reduces it to 80
your items subtract another 41.4 (rounded down it's 41), so now it's down to 39.
Then, you take 40% and subtract it from the remaining amount, bringing it down to 24, for a total loss of 76 magic resistance.
Even if your opponent has 200 magic resistance, you're leaving him at 83.4 Magi resist, a lost of 117. The larger the amount of Magic resistance, the more the penetration percent helps, which is why it's better to take void staff later in the game than early.

now that magic resistance no longer an issue, you're free to go to work on the enemy team.
You should have upwards of 280 bonus AP at lvl 18:
- 50 + 30 from Will of the Ancients
- 80 from Rylai's Scepter
- 50 from Lyandry's Torment
- 70 from Void Staff.
- 18 at level 18 (blast mastery)
- 6 (mental power mastery)
For a total of 304 +5% (arch mage mastery) = 15.1
So the grand total WITHOUT the last item is 319.

Now's the time to decide upon a last item.
If you couldn't find someone to get an abyssal scepter for you, you should definately take it yourself. 70 AP, 45 MR isn't bad, and as you saw above, the extra 20 MR reduction this thing brings can take someone with 200 MR down to 83 MR.

However, if someone else took it, or the enemy team didn't think it was a good decision to use MR for some reason, you have other options, the obvious being the Death Cap.

the 120AP + 30% boost is definitely going to get their attention.
304AP + 120 AP = 424AP + 35% (Death cap passive and your mastery) gets you an additional 148.4 AP, bringing the total to 572AP.

At level 18, your lightning rush deals 245+(60% AP) in damage, or 598 magic damage (245 + 343)
With the extra 2% damage you do with havoc, that adds 12 to your over all damage output.
If the target is at 50% health or lower, you deal an additional 5%, bringing the total bonus damage dealt to 42.
598 + 42 = 640 Magic damage dealt from your E alone.

Electrical surge grants another 185 +(55%), 185 + 314 = 499. 499 + (7%) = 534 Damage out put to targets at 50% health or lower

Thundering shuriken adds 235 + (75%) = 1,001 + 7% = 1,071 damage output to targets at 50% health or lower.

so, through the extra 7% damage from our masteries, our abilities do 146 more damage to enemies than before, and a grand total of 2245 Damage dealt, excluding your ult.
Not only this, but you also gain 449 HP (20% of 2245) from Will of the Ancients 20% life steal.