I really do like the build. I don't really play as Kennen a ton and I don't really know what makes a good Kennen, but I know that he is a champion modified by AP and this looks like AP. All I can say is great job with the Lich Bane. This gives him that bonus movespeed and that boost to his physical attack. The Moonflair Spellblade looks really good in your build comp. It just gives your Kennen some good Tenacity to support your 21 points in defense. I wouldn't go for your main boots lost though. The spell pen that you can get from them is really needed unless you're going for the Void Staff. In my opinion, this is a pretty good build. +1 might wanna add some pretty pictures to make it easier to read though.

You forgot to take ur ulti at lvl 11 ;p even though kennen is squishy i still like to take scor shoes because tbh he is so goddam squishy that even with merc treads he will still fall over when focused, but 9/21 is perfect for him and the items are basically the same way i build him which never fails for me +1