The reason why I pick so many Rabadon's is because I like to play kennen as so much dps as I can. U got the Hourglass or u can choose the Abyssal Scepter. So thats enough for resistance coz u got ur "e" spell. Rylai's is good for the healthboost so u dont be to squishy. With this build u got 914 ability power at lvl 18 thats enough for me. IF they've got to much magicresistance u can buy one Void Staff and remove one deathcap.

When I play kennen I always go mid. I got the full rune at lvl 1 so its easy to get first blood. First blood means 400 g and extra item. Extra item means better items before others itemcap. so I think AP at low lvl is important. I trying to get him into half hp and I suggest u gank at lvl 3-6+. When he got half hp make sure that there isnt to many minions in the way. Go with ur "e" spell quickly W and nuke with Q. U got flash and e for hunting and ignite for extra damage. At lvl six u can do exavly same but do ultimate before w so it will be this order: E,R,W,Q. I see e as the escape button and tiny damage so I leave it with one skill untill im forced to learn it. I buy boots of swiftness coz I like to get out of ganks quickly.

Dont be the tanky in this build! Even if u got pretty much hp let them focus on a teammate and go in quickly with the , E,R,W,Q, I suggest u save flash for escape. Do never go first at ganks coz if they got u in snare, stun, u are dead!