From what I gather the reason AD Kennen is even being discussed is because M5 won a tournament and had an AD Kennen. However, as someone pointed out in a thread I found, they played insanely well as a team. Point being, the other team couldn't or didn't exploit this build.
So AD Kennen has been used by at least one pro, which I never doubted, but figured I'd point out since it has been discussed.
Now, it must be noted that even AD proponents say that AD Kennen is insta-fail unless you also are going AS. See, the whole point of AD Kennen is to hit really fast to utilize the stuns, and the single ability he has that benefits from AD.
That ability is the passive on his W:
Every 5 attacks, Kennen deals magic damage equal to 40/50/60/70/80% of his attack damage and adds a Mark of the Storm to his target.
Mark of the Storm?
Kennen's abilities add Marks of the Storm to opponents. Upon receiving 3 Marks of Storm, an opponent is stunned and Kennen receives 25 energy. Has a diminished effect if done twice within 7 seconds.
That's it. That's why folks play AD Kennen. And again, if they're not focusing AS with runes and masteries and items, they're doing AD Kennen wrong.
Now, the quick attacks and stuns sound great right? Well, here's the downside:
Kennen's abilities -
Thundering Shuriken - Kennen throws a fast moving shuriken towards a location, causing damage and adding a Mark of the Storm to any opponent that it hits.
Throws a shuriken that damages the first enemy it hits for 75/115/155/195/235 (+0.75) magic damage and adds a Mark of the Storm.
Electrical Surge - Kennen passively deals extra damage and adds a Mark of the Storm to his target every few attacks, and he can activate this ability to damage and add another Mark of the Storm to targets who are already marked.
Passive: Every 5 attacks, Kennen deals magic damage equal to 40/50/60/70/80% of his attack damage and adds a Mark of the Storm to his target.
Active: Surges electricity through all nearby targets afflicted by Mark of the Storm, dealing 65/95/125/155/185 (+0.55) magic damage and adding another mark.
Lightning Rush - Kennen morphs into a lightning form, enabling him to pass through units. Any enemy unit he runs through takes damage and gets a Mark of the Storm.
Kennen moves very fast and may pass through units, dealing 85/125/165/205/245 (+0.6) magic damage and adding a Mark of the Storm to any enemy he passes through. Additionally, Kennen will gain 10/20/30/40/50 armor and magic resistance for 4 seconds.
Kennen is refunded 40 energy if he passes through an enemy, but can only gain this effect once. Lightning Rush deals half damage to minions.
Slicing Maelstrom - Kennen summons a storm that strikes at random nearby enemy champions for magical damage.
Summons a magical storm that deals 80/145/210 (+0.4) magic damage and applies a Mark of the Storm to a random enemy champion near Kennen every 0.5/0.4/0.33 seconds. This storm attacks up to 6/10/15 times and cannot hit the same target more than 3 times.
See what's happening? If you go AD, you're ignoring all the bonus damage because your abilities scale up based on AP.
Also, in the threads I saw, it's pointed out how Kennen is not a 1v1 champ. He's meant to harass and be a major part of a team attack. Note that 3 of his 4 abilities can affect multiple champs... AD Kennen can't do that, well he can, but for little damage. AP Kennen hits hard with those abilities.
So the vast majority of players think AD Kennen is not a good idea because you're building him in contradiction to his strengths.
