Hey boards, some of you probably remember my username. I went on a bit of a hiatus from league and looking back, a lot of the ideas I posted were definitely salt inspired. I stand by a few of them but a majority of them were definitely written in bias. That being said, I have a few new ideas that I'll spread out in a couple of post.
Probably the only reason I got back into league was to play Kayn. Design wise, he is really cool (albeit edgy). It seems kind of weird honestly that Riot would release an assassin in a weak state but I'm not going to suggest buff ideas for blue form. The base passive feels kind of clunky in the way it works. You could kill several ranged champions to get an almost full bar, and then kill one melee to finish it and it will give you red form.
I personally think the passive should give you the form for whichever you've killed the most. Also, waiting four minutes to choose the other form can put your team at a serious disadvantage in a lot of situations. Sometimes you'll end up falling behind early which will delay your form change and will create a seriously frustrating mid game.
To kind of put those thoughts together, let's assume the enemy team is composed of Darius, Zac, Syndra, Braum, and Caitlyn. No real reason behind the champions but for the most part I think you would want red form for that kind of team. You gank top once or twice and skirmish with zac in jungle. Bar is almost full of red orbs because you've been fighting melee champions. Syndra tries to help zac counter jungle you and you end up killing her. This fills your bar and you have the option between getting blue form or waiting till mid game to get red.
This is a serious problem because if you get blue form you would probably end up dying to syndra or darius pretty easily. But by not getting blue form, you sacrifice some of your mid game and hope you can turn it around later. I think there's a simple remedy to this. On top of what I mentioned above with getting the most commonly damaged form, killing people for the other form should reduce the timer you have to wait on it. So if I could get blue form, I could also go out and deal some damage to their melees to get red faster.
Those passive changes would ideally be a good start but Kayn has an inherent problem where red form is most likely going to be a better pick then blue form. I'm hesitant to suggest a damage buff to kayn in general because both forms can definitely output good damage, but if I were asked, I would say that blue kayn's q could use a damage buff. It feels incredibly weak in comparison to rhast q and it doesn't feel much stronger than base kayn's q either.
Those are my thoughts on Kayn, mostly his passive, but Riot should definitely wait on changing him for a patch or two after this buff. Over tuning is a serious problem this season.