Not Updated For Current Season
This is the best Build for Kennen.
Kennen is one of the OPest champs in the game, thats what i found out :O
Mark of the Storm.
Kennen's abilities add Marks of the Storm to opponents. Upon receiving 3 Marks of the Storm, an opponent is stunned and Kennen receives 25 energy.
This is what makes Kennen such an annoying opponent. if you ever want to kill someone, you HAVE to get marks on them to stop them from running.
Kennen throws a lightning shuriken to a target location, dealing damage and adding a Mark of the Storm to the first enemy it hits.
This is like your most important spell, you should use it whenever its ready if you can. Use it as an opener when you've targeted someone you wish to kill. Use it to harass, which is why you should max it first! this also makes kennen able to last hit even if the enemy(ies) in the lane hits hard and you cant get in auto attack range.
Kennen's weapon becomes charged every few attacks, dealing extra damage and adding a Mark of the Storm on his next attack. (Active): Surges electricity through all nearby targets afflicted by Mark of the Storm, dealing damage and adding another mark.
If you hit an enemy champion with TS, you should try and follow it up with ES, it will make them run away in fear for you to get the third mark(but if you actually wanted the third mark you could easily get it ofcourse :P). you can use this for many other things too ofcourse(provided you already have marks on your target(s) )
Kennen turns into a pulsating ball of lightning for several seconds, gaining 230 movement speed and the ability to pass through units. Any enemy unit he passes through is dealt damage and receives a Mark of the Storm. Upon hitting the first enemy, Kennen gains 40 Energy. Half-Damage to Minions.
This is your Chasing/Escaping mechanism, you can also use it for farming if used together with ES, and when you have Haunting Guise you can use it(with ES) to regain health. remember, you can run straight through units while this is active too. If you put your eyes on someone to kill, you can use this straight after TS if TS did or did not hit, if it did hit you can use it to get in range to use ES, and/or get up next to your target(adding a mark on them). If TS didnt hit you can use it as soon as youre close enough to touch them with LR and use ES afterwards, they will often turn around and hit you, because they follow the tip "Kennen is flimsy by nature - turn around and attack him if he gets careless with Lightning Rush", this gives you an opening to use your TS(this counts if they run too because they will be too close to be able to dodge). And yes usually TS will be off Cooldown in time. In other words, LR has VERY many uses.( from other build)