Since Kennen is being nerfed again, here are some opinions.

It seems as though Riot has their sights set on nerfing Kennen once again, thought this time its to his on-hit variant rather than his AP variant. I saw this coming, as Riot definitely doesn't enjoy letting lane bullies see the light of day for too long. Though I don't think nerfing him is necessary, I'm not the best person to ask about this build and how healthy it is in the current meta, as I don't play his on-hit style. I'm here to speak on behalf of AP Kennen.

AP Kennen has been in a terrible place since he was nerfed in the 7.1 Patch. For those who don't know, his old ultimate started off doing 80 (+40%) damage on the first strike, and then decreased with each successive strike by 25% down to 50%. This was changed during the 7.1 patch to start off doing 40 (+20%) damage, and then ramp up by 10% with each successive strike. They passed this off as a "buff for good Kennen ultimates". However, I'd like to go into detail as to why this is completely false, why it was a nerf, and why if AD Kennen is getting nerfed, AP Kennen deserves some sort of compensation, lest he be left in the dust completely.

Riot's reasoning behind the ultimate change was that Kennen's ult did too much damage before the enemy team could respond. This is a totally legitimate argument you could make. However, their response to this seemed entirely ill informed, and seemed to be more based off competitive hype, low elo play, and a certain Smeb ultimate than reality. Riot attempted to pull off the change as a buff. In some way that is true, but in all practical applications in game, it is a nerf. At levels 11 and 16, your ultimate does more damage, but ONLY on the very last tick of his ultimate. For example, if you land every tick, the base damage on your ultimate at level 16 now does 825 compared to the old ~788, and that's not considering scaling. Seems fair at first glance, but I'd like to explain why that literally doesn't matter at all.

No competent player is going to stay in a Kennen ultimate for a full three seconds. I'm not trying to stroke my ego I promise, but I'm in Diamond 4 and I don't think I've ever landed a full 6-tick ultimate on anyone other than in a 1v1 situation. I find that around plat elo, people learn how to build and play against a Kennen ultimate a lot more. This means that, although on paper this is a buff in some situations, in reality it is a nerf in almost every single teamfight situation. It's a common misconception that there is not counterplay to a Kennen ultimate, but in reality, there is a TON of counters to his ultimate. I won't include summoner spells in this list cuz that's a bit of a cop out, but I would like to point out that avoiding his ultimate with an SS is more effective against him than many other champions, as he is so ult dependent. Kennen counterplay includes: hexdrinker, merc treads, locket, redemption, QSS, adaptive helm, Zhonya's, any form of CC to catch his ultimate early, shields, dashes/escapes, and knockbacks. Any of these things can be used to survive a Kennen ultimate. Some thing like banshees and GA could count as well but were too situational so I left them out. Kennen's ultimate is his most important tool, and without it he is fairly lackluster, so countering a Kennen ultimate is very crippling too him, and there are a lot of different ways for smart players to do it.

Now I'd like to explain why Kennen needs more damage at the beginning of his ultimate. As I've said, there are plenty of ways to get out of a Kennen ultimate or negate his damage almost completely. On average, Kennen is more dependent on the first 3 ticks of his ultimate than the any other, as good players can and WILL get out of his ultimate beyond that point. Kennen is played as a burst mage, meaning he needs to get off as much damage as fast as possible, generally on the enemy backline. I don't think this is a problematic playstyle at all. This is how all burst mages, and many assassins in general, function in game. The changes to his ultimate shifted him away from this style of play, the one that works, and put him on an awkward path of more sustained damage, or as peel to threaten enemies who stay in your ultimate for too long while trying to get at your backline. This just doesn't work for Kennen's playstyle. Kennen is incredibly ult dependent, and essentially wants to blow his load as quick as possible, Zhonya's before he takes lethal damage, and pray for his team to clean up the rest. Putting him on a path to more sustained, over-time damage is not healthy for him and doesn't work, and that's why having the first ticks of his ultimate do the LEAST amount of damage is the worst possible change that could have been made to him. It's why pro players have dropped him completely. It's why his win rate has dropped ~4%. It's why it just wasn't fair.

There are solutions to this. As I've said earlier, despite the fact his main items were already nerfed prior, the argument can be made that his ultimate did too much damage beforehand. But reverting the changes aren't the only option here. I do think that his ultimate should do more damage at the beginning. For example, the initial tick could do 60/108.75/157.5 rather than the old 80/145/210, and then taper off down from there to still do the same amount of max damage as the old one did, which is less than the current one. That's still 25% less initial damage on the first tick, and could even further be tweaked to be a little less front forward if need be. If you're still hesitant to implement these changes, the very least that you should do is make it consistent all the way through. This means an even (50, 93.75, 137.5 [+25%]) per tick all the way through: not front focused, not end focused. This way its even and consistent, and doesn't punish Kennen for his designated playstyle. Either way, I'd really hate to see AP Kennen untouched after nerfing his on-hit counterpart. Kennen means a lot to me and I hate to see him get constantly nerfed like this. I'm in a place where I get more success playing him as support than anything else because of how unimpressive his damage has been for such a long time. Sorry for the wall of text, I just had a lot to say. I'd appreciate any feedback, positive or negative, and I'd love to respond/clarify anything I've said.