Kayn needs work still.
Going to keep this short, since Spectrum SUCKS and my internet keeps cutting out and deleting this entire thread.
Rhaast still sucks, but is doing better since the Ardent meta died down--he isn't imploding as easily anymore, but still is underperforming in comparison to other bruisers. Very minor scaling adjustments are probably in order.
4min Transformation timer is TERRIBLE and needs to either be removed, or there needs to be a fast forward mechanic to speed It up. 4mins of mid game is WAY to much time to be wasting as base form Kayn because you got the wrong form, often times its just purely unavoidable. He should just be allowed to freely choose Rhaast or Shadow Assassin when his Transformation bar fills. I don't care about this whole "cool" idea they had where hitting ranged characters makes u an assassin, and hitting melee makes you a bruiser. its a cool concept, but its debilitating and is obviously a bad implementation.
Shadow Assassin is both overpowered and underpowered at the same time. For those who don't know, Shadow Assassin, shares the same weaknesses as Zed, however those weaknesses are magnified on Kayn. Zed can perform outside of Deathmark. Kayn cannot perform outside of his R. What this means is, Zhonyas, GA, and Locket, COMPLETELY negate Shadow Assassins entire existence, whereas for Zed they are really just a hinderance. Another fun tidbit of information is, Shadow Assassins scaling isn't up to par with other assassins, Ninja Tabi alone on a ADC or APC are enough to survive his full rotation and completely negate his entire existence. In short, Shadow Assassin doesn't have the killing power of a real assassin. This is attributed to his insane mobility, but his mobility is irrelevant if he literally cant do anything, even to squishies.
On the otherhand, his mobility is way overtuned and is incredibly oppressive vs inexperienced players. He can just weave through the map and delete anyone who doesn't know how to exploit his weaknesses. Which is most of the sub-plat community.
I really feel like they need to relocate some of Shadow Assassins power from its mobility, into its killing power. Ninja Tabi aren't enough to stop any other AD assassin, Mercs aren't enough to stop any AP assassin, this should be true for Kayn as well. But its not. Nerf his mobility, put way more power into his Q, up the scaling on all of his abilities. Reduce the damage W deals to minions if need be(to prevent him from 1shotting entire waves.). I'm okay with GA and Zhonyas completely countering him, since he's kind of a generalist champ BUT a pair of boots shouldn't be having the same effect.