addendums:
1* I have Switched from Phaserush to Electrocute do to higher damage from poke making laning phase easier.
2* You can choose to go Thundering Shuriken first - but I tend only to do that when I feel I have to be max range. It can be use to harass at level 1 but I procure it first if I need assistance farming.

I show only T1 boots as your need for either MR, armor or Spell pen will depend on the game. I want to talk about The secondary build. This is a hybrid build that I don't see many people looking at. The reason Why this build exists is when the rest of your team is losing.

If you have seen this Guide before you would have noticed Nashor's Tooth in the lineup. After putting a few dozen more games under my belt - the extra attack speed is not relevant compared to rushing Morellos. It is still a good choice if you are stuck in a farming lane till the end of the game but overall not worth the displacement of other items.

New lineup - untested - Items that seem interesting but have yet to have trials done. Lichbane: since players like tryndamere are using essence reaver which gives mana why not try Lich Bane since it has all the other stats I like. Liandry's Torment: Seems functional with kennen if not good but I do not know if it's good enough to take a slot from the other items. Rylai's: Solid item If you need to go defensive but has yet to be seen if the slow if effective enough. Adaptive Helm: I included this item for if you need to be the initiator. In theory If you are against a high AP team, this allows you to get in the backline without being blown up.

Talent 1 I am using Electrical Surge because it's more consistent even if it's less power. consistent damage > top power is my motto.

Kennen is a Hybrid champion focused around poke and group fighting all-ins. His Shuriken is a skills shot that hits the first target it comes in target with. It is the most powerful damage ability he owns other than his ulti. Electrical Surge has two abilities. Its passive gives your auto a passive stack every 5 attacks. The active is hits all targets that have his passive Mark of the Storm on them. His Lightning Rush is a mobility spell that allows you to proc your passive on anything you touch while in this form as well as speeding your character up. Lastly is his Ulti which is Slicing Maelstrom. This is a large AOE ability that procs your passive every .5 seconds stunning everyone in a max of 1.5 seconds.

Early:
Get that poke on. Since you have started Electrical Surge, Make sure every 5th attack is on your enemy giving them a passive stack of Mark of the Storm. This will cause them to back off from the wave as your Surges active will cause more damage to them than missing a farm or two. If they do walk up. activate your surge and they will be chunked. When you get Shuriken at level 3 - don't be afraid to use it as a farming tool while using your autos to pressure your opponent. While extra damage on them would be preferable > lane control is better in the long run. Keep that farm up and keep focus on keep them from not farming.

Mid-game:
You hit level 6. You have two options at this point: roam or stall. I don't feel Kennen is a very good tower sieger especially when the plating is still up ( that being said if you are way ahead this does not matter.) SO my goal while playing Kennen is either freeze the lane so they cannot farm and you gain those advantages or roam. Freezing is only a good strategy when either your team is also all winning OR you are behind. Secondly you could go gank for other lanes. Personally I attempt to never use teleport past the first one to get back to lane so I have that availability to travel to other lanes quickly. The best way to accomplish this is by hard pushing the wave all the time then looking for places to make plays. IF there are no lanes open to make plays in lane - get deep wards down and try to get some of the opponents jungle to put them behind.

Lategame:
You did it you hit late game. What ever build you chose to go for, you will want to be in a side lane. With your mobility it is easy to flank during a fight this is the best place for you. Push what ever lane is best for your team while keeping an eye on them. If they are behind and you feel like they cannot fight even with your power of a 5 man ulti - relay the information that you are pushing and that they should not engage. If they back off too far and the enemies go for you you can just Rush away. On the other hand if you feel like you can be use to them in a group fight - when you think they are about to fight, go into the fog of war. straddle yourself between the two lanes this way if they engage you can be there with your ulti and ready to join the team. But if they back off you can go back to pushing to those towers.

Melee range conflict. Kennen is one of the most squishy champions in the game. If they get on you for any reason and they either have a slow or your Rush is down - you are dead.

Being over confident. Because it is easy to snowball with this champion it is easy to get cocky. But because he is so physically weak going anywhere recklessly can be your demise. Any CC will ruin you.

When an opponent wants to trade then run away follow them and auto. If you believe that their dash is down keep going till you feel unsafe. I was too passive when I first started top lane to do this. Since I have, I have started win lanes much harder.

Use Rush sparingly. It feels really nice to use rush to hard push the lane, BUT this opens you up to ganks and or all in by your opponents.
addendum clause: If you are under tower a Lightning Rush on the mage minions will give you the position to only need to give them 1 auto after tower shot. This makes it an easy way to set up your minions.

If you don't have Hextech or flash - do not try to run into their team to get your ulti off. Either go into the fog of war or just keep your autos up. If you just Rush in - you'll just die. I also suggest waiting for Hourglass if possible.

Don't be afraid of taking risks during objectives. There have been many times where I have flashed into baron or dragon to attempt to steal. Even If you don't get the objective you may have gotten a few kills for your team as you stun and damage their team while your's shows up.

As you can see there are two rune pages given. One running Spellbook and one running Electrocute. Spellbook is a spicy runepage for control over the map. You can start with Ingite/flash. Switch flash for Teleport, go bot ingite+ulti win the team fight. Late game you can switch ignite for barrier flash deep into a team. Downside: your solo laning phase is forced to playing scared. Electrocute is a huge damage buff doing around 250 damage with a level 2 q[empoweredauto]w. Great to get ahead in lane and snowball. Lategame it's good if you are ahead, even better if you are building hybrid damage.