I consider myself a Kai'Sa main
And I consider her very, very unhealthy. I think she's in an ok spot atm, balance wise, but the fact she can build any kind of damage, damage/defense hybrid item and lose nothing for it is extremely unfair and impossible to properly balance around. I think Riot actually missed a very good opportunity here to make leagues first adaptive champion. Like imagine a world where Kai'sa could build AP or AD, but not both.
But fear not, I came with a proposed solution, not just with the 10 millionth complaint about Kai'sa.
SECOND SKIN Living Weapon: Upon reaching either 100 AD or 100 AP, Kai'sa's scaling become adaptive.
Example: Kai'sa's w has a 150% AD scaling and a 60% AP scaling. Once reaching 100 AP, the AD scaling would drop to 0%.
ok, but what would this do?
Well, this would make it so Kai'sa can't have a phantom dancer, guardian angel, a Zhonyas AND STILL be able to out damage every other ADC. It'd make her have to think just a little harder about what she can/needs to buy, while keeping her identity as the flexible build ADC.
Ok, sorry for the word vomit, that's about all I got. Thank you for listening, friends.