Hi, this is my first guide here on Mobafire. I hope that you will find it good! This guide is focused on Kennen, the Heart of the Tempest. Thanks to ThatRicoGuy for the idea, but my build is slightly different. As well, thanks to jhoijhoi for the build guide which can be found here.
-Tons of damage output
-Stun, good for CC
-good area damage
-Good in teamfights
-squishy early game
-slow early game
Early Game / Abilities
Early game, kennen is a bit squishy. I find this quite annoying. As ThatRicoGuy said, it is much more useful to get a doran's shield to begin. I, too, used to start with an amplifying tome, but I ended up recalling too much.
Kennen's Shuriken does tons of damage. I rank it up first, both for lasthitting minions and for harrasing the enemy. As well, it is good for bushchecking. If you have a hunch that someone might be in a bush near you, don't hesitate to throw a shuriken into it to check. If there is someone in the bush, the shuriken will flash for a second before going through them, and not travel as far as it should if there was nobody there. As well, if you have Electrical Surge, you will notice it light up, showing that there is someone in range. Your Lightning Rush is good for both chasing and getting away, but the damage it does is not too great, so I rank it up once early game then max it last.
When you are being ganked, a great way to escape is with your Lightning Rush. This may be a bit obvious, but using it to go backwards to hit them and head in the opposite direction is also good, as it is an unexpected move that does damage. If confident of getting away, you can use your Electrical Surge to hit them, and if you are being ganked by someone squisy, you can use your Slicing Maelstrom.
Kennen's Slicing Maelstrom is very powerful. It guarantees a stun on anyone that is within the radius, and as a bonus, you can use your other abilities while it is active. Zhonya's Hourglass works well with it, as if you are low health, you can get a stun and get away / get a kill, if you Zhonya's and then ult.
It is relatively easy to farm with Kennen. You just hit all of them with your Lightning Rush, and then use your Electrical Surge to hit all of them. However, early game, this will not be sufficient to kill a minion, so focus on last hitting with your Thundering Shuriken and your autoattack. If you ever get low health, if you have your Will of the Ancients, you can leave the lane for a couple minutes. Focus on hitting jungle minions through the wall with your Thundering Shuriken, to restore 50 health at a time. This is also a good reason to rank up your Shuriken, to have less cooldown and to do more damage.
Tip: NEVER, NEVER use your Slicing Maelstrom on minions. That is the most retarted thing you could do, and I know this from experience, as when I was a noob, I would do that all the time. However, just let me clarify here: Slicing Maelstrom DOES NOT hit minions.
Kennen is a great ganker. His abilities and his passive work great for any sort of gank, and he is even excellent in 2v1 ganks (with him being the one.) For ganking, I lightning rush into both (or one) of them, hit one with my Shuriken, then Electrical Surge them for a guaranteed stun on one of them. This will be enough to get most non-tanks to at least 2/3 of their health, and when they realize that there is only one of you, they will move in to kill you. However, your Slicing Maelstrom will get you a stun on both of them for sure, and by then your Lightning Rush will probably be back off its cooldown, which ensures you another hit on them. If they have not died yet and are starting to get away, you can either:
1. If you know they will get away, you can simply leave them to recall and let your teammate(s) push the lane, or
2. You can chase them with your flash and use your Electrical Surge and Thundering Shuriken to get a stun, and finish with Ignite. Ignite is also a good idea somewhere in the early stages of ganking as well, as it can scare an enemy into running away.
However, if you are facing anyone with lots of sustain and attack speed (A fed Master Yi is a good example), this would be a good time to run away, or if anyone else on your team is ganking them, to let them get a kill. Even with a Rylai's Crystal Scepter, that might not be enough to ensure a kill, and the gank might fail if you are attacked by a Master Yi with lifesteal and Phantom Dancers.
Mid lane / General Gameplay
For Mid Lane, which is how I normally play Kennen, you must be able to land your skillshots, whether on an enemy minion or a champion. His Thundering Shuriken has massive damage, and also works with his passive. Against someone like Ziggs, you must rely on your ability to dodge his Bouncing Bomb and work your way around his Hexplosive Minefield. If not, then you will probably not succeed. Ziggs, I find, is very effective against Kennen. As well, (this is a noob tip) never focus a tank with your abilities, as their damage output is low and you can pretty much ignore them. A Tanky DPS, on the other hand, like Wukong or Nocturne, is the bane of a Kennen, especially if they gank you. You must have good map awareness, because then you will be able to time both your ganks and when to run away/recall. As well, if they have a tank that does damage and is almost impossible to kill, I would encourage you to get a Deathfire's Grasp for the 30% of their health damage.
Items, Runes, and Masteries
For Items, Kennen should have spell vamp and a health AP item, otherwise he will be the squishiest champion on your team and constantly focused. A Zhonya's Hourglass will help you in case you are focused constantly. I encourage you to NOT get Archangel's Staffs, as you do not have mana. As well, a Lichbane for lategame works really well, as Kennen's Lightning Rush helps him to close the gap in between champions, and Lichbanes work with his stun. Even though Lichbane is a Mana item, Akali and Kennen both benefit from it.
For Runes, you need some magic penetration for early game, and then flat AP. As well, I go for Armor runes, so that I can take less damage from minions and enemy autoattacks (Twitch in mid is very annoying.) Later in a game, you will be more dependent on his stun than magic penetration, but if you have any ideas about this, feel free to comment. (I am not 100% sure about this part.)
For Masteries, I DID go with a couple points in Utility so that his Flash gets up to its maximum potential, but I changed it to a more defence-oriented tree, as it gives you a bonus 36 health for early game, which can be the difference between life and death. Kennen's no Tryndamere. I go for a lot of AP masteries, and for damage as well. Notice that I did not pick anything for AD. I sometimes go hybrid Kennen, but not too often. A lichbane works just as well as any critical strike. (You can comment on this, as I never go flat AD Kennen, so make your own suggestions if you feel any urge to.)
For Summoner Spells, I go Flash, and Ignite is optional, and here as well, feel free to make your own suggestions, as other skills may work well, too. I go ignite to work with my stun, so that in early game, I can get off extra damage in case someone escapes behind a turret.
All in all, Kennen is a strong AP that can do massive damage and get fed like crazy, if you play him well. His abilities make him somewhat easy to play and make him a very quick damage dealer. Feel free to post comments with your ideas to improve this, as this is my first build. Thanks for reading!