kennen after the patch 4.21 becomes op and too much op so i can tell u to buy it cuz when i play with kennen i never lose

pros:
low cooldown(only the ult have a high cooldown)
high movement speed
high farm
high damage
no manna she have energy
amazing passive
cons:
high cooldown for ult
not so easy to play
need too much focus

first of all u start with the doran's blade and one potion
and then u get liandry's torment and then the boot and then zhonia and rylais and then dfg and finally the hat

let the jungler come to gank
when he ganks open immediately ur ult to stun the enemmy and then do ur spells he will be stunned another time so 95% a kill