kennen has a VERY damage output mid to late game. your main harass tools are your Thundering Shuriken, Electrical Surge, and your Electrical Surge passive. If u are able to land Thundering Shuriken at least 50% of the time you will have no problem. i like to play kennen in mid because he uses energy in place of mana which can give you limitless harassing. by end game you should have your oponents crying at the power of your ult.

pros
very high damage output earlier game fights
great mid
very hard to hit with skill shots do to lighting rush
good dissabler for like fiddles and miss fortune
cons
very squishey
bad agensed very high helth targets like chogath, nunu, and amumu.
is targeted after the other team sees how badass you are and how fast u kill there guys

i will be adding this later when i have more info on the best way to do it in the mean time just last hit with Thundering Shuriken and enjoy the following message. zap zap zap zap zap zap zap zap zap zap zap zap zap zap zap ZAP ZAP ZAP ZAP ZAP ZAP ZAP ZAP ZAP ZAP ZAAAAPPPPP

still trying to find more info till i do just gank as much as you can cuz you will be playing mid and try to hit as many people with Lightning Rush and Electrical Surge during team fights now enjoy a spcial word from kennen him self. ZAP ZAP ZAP ZAP ZAP ZAP ZAP ZAP domacieaaaaa nooo zap zap zap zap DEAD thank you for your time

i like the hp quintessences becouse kennen is quite squishey earlie game same with the seels and the extra ap and magic pen is always nice

i like the 9 21 0 for kennen because he is just so damn squishey that and it will make you go crazy if u half to go back and forth from ur spawn pool to the lain befour u get the hextech revolver. the offence masteries will make it so ur burn will finish them off when they run insted of bringing them down to like 10 helth and making first blood all the easier.

i take those items because they give you crazy ap and survivablity from the spellvamp you will be heeling 100 damage every ninja star by end game. if your fighting a hevy cc team id switch out the lich bain or zonyas hour glass for a sunblade so you cant get ccd as well

i like to harass with my thundering shurkien and electrical surge just to brieng there helth down to about 75-50% then i leed with lightening rush to add a mark and get behind them followed by electrical surge and sliceing maelstorm and i then hit them with thundering shurkien and electrical surge when ever there cooldowns are up.

i like to take flash and ignite they are really truly the best spells for kennen you can use flash to escape a gank you can use it to jump on a target when lightning rush is in cooldown and its just an amazing spell to have in your back pocket. ignite is just an amazing spell for first blood and has some crazy use when fighting people who can heel like mundo, nid, and any of those noobs who use the heel summoner spell.

ty for reading my guide i hope it helps you and dont forget to comment and tell me how i did first guide n' all and definitely dont forget to harass with thundering shurkien and electrical