Against kennen, Kennen’s power spikes depend heavily on the items he buys. 

At level 6, Kennen will get access to his Ultimate m which is a great tool for him as it increases his kill pressure and his ability to trade with you. As soon as he activates his Ultimate m, run away. 

Kennen is really good in team fights thanks to the AOE damage on his Ultimate m. Try and avoid fighting in tight spaces as Kennen will be able to deal damage to your whole team at once. Group but do not group close together.  Against kennen, At level 6, Kennen will have access to his Ultimate m which is an excellent tool for him because it increases his death pressure and ability to trade with you. As soon as he activates his Ultimate m, run. Kennen is really good in team fights thanks to the damage of the AOE on his Ultimate m. Try and avoid fighting in tight spaces because Kennen will be able to inflict damage to your entire team at once.