I played Kennen on ranked and normal games long time. He is a very good champ. I had a lot of fun with Kennen. He is great AP carry in early/mid game and disabler in late game.

x9 To do some dmg.

x9 I recommend kennen on top and it's a survi for him.

x9 Dmg.

x3 And....... DMG!

9/13/8
It's unusal masteries, but it works.
9 in offensive to dmg.
13 in defensive, because Kennen must be in the middle in teamfight.
8 in utility for increase the amount of experience.

This item is good on Kennen, because Doran's ring give mana regen and it doesn't give survi(only 100 hp). It's build for a solo top Kennen and he need survi.

Dmg and speed to mobility and dodging skillshots.

Ability power for us and spell vamp for us and for teammates.

HP, ability power, and great passive. Kennen is good at using this paasive ,becuase he have AoE spells and short cooldowns.

AP and armor+ great active. It's so wonderful to launch ulti run to enemy and launch this item. Now we can smile to Alistar.

If game doesn't end we buy this item to maximize our dmg.

Another great item to maximize dmg. If game doesn't end we sell Doran's shield and buy this item.

We max Q.
If Q isn't possible we give W
E on level 4 to escaping ganks.

My proposal

The best summoner spell in this game.

Your enemy never runs with low hp.

Pros:
-Energy
-AoE dmg
-If you use ult and team don't run teamfight is usually won.
Cons:
- Kennen is very dependent on team

You can last hit with Q, becuase energy regens very fast. Harrasing with Kennen it's very easy. Load your paasive from E, use it on enemy, next W then E and if your enemy is stunned you can aim shuriken and run.

It's my first guide and I want to see your comments ^^.