This Kennen build is rather unconventional.
I go for attack speed and a bit of tankyness so you can get in and out nicely.
I would say it is a more skilled version of Kennen.
Harass with a lot of auto attacks in order to pop your W's passive and Ionic spark's passive too.
Don't be shy to run back and forth to avoid melee engagements. I find going face to face with like trynd or someone makes it a lot harder.
Auto attack enemy hero as much as possible if they take cover through creeps and farm.
If they make a move on your pop your E and touch them and run away to get a spark on them.
Always keep distance.
This build is a good tower diver, Save your E for when you are getting hit, it provides nice defense, and you cannot auto attack during it so beware you lose a lot of dps during.