Kai'Sa buffs
I kind of knew this was coming since even after the Aphelios/Senna nerfs, and the changes in 10.5 Kai'Sa's winrate and pick rate have stayed around the same, but I'm starting to think that this is a really bad idea. I don't have the data you do /u/RiotAugust (at least, I'm pretty sure you're the one working on these right now), but I can still contribute my perspective.
Why is Kai'Sa at sub 47% winrate right now in Plat+, and why has she been like that the last few patches?
Indirect nerfs, botlane power creep, and a suboptimal meta. By this I mean a few things:
- Stormrazor nerfs, Rageblade nerfs (this was a while ago), and ranged champions being adjusted to do less damage to turret plates.
- The existence of Aphelios (who literally has a gun for every situation, 200 years) and Senna (who gets to be a support and ADC at the same time with no reprocussions, 200 years). Seriously, these two give Kai'Sa a run for her money when it comes to the term 'overloaded' and trade mobility for obnoxious sustain, range, and CC - all of which are far more useful to a team even when they're behind.
- Suboptimal meta. Contrary to popular belief, Kai'Sa doesn't have the easiest time versus tanks (at least not since the various nerfs AP Kai'Sa recieved post 8.11), and not being able to properly itemize Grevious Wounds since you're almost always going to go Rageblade only makes the situation even worse. Kai'Sa thrives in a meta where she can win any duel on the map, and this isn't that meta (especially w/ the brusier buffs).
Now of course, even with all of these in mind Kai'Sa is still doing fine, and you have to remember that she's an extremely popular ADC with an above average skill ceiling. However, it's exactly because of this that I'm so afraid of Riot giving her any more buffs - Kai'Sa is already doing OK, and she's even been able to start popping up in pro play again because of the Senna/Aphel nerfs turning them down a notch. The moment the meta shifts in her favor or she recieves an indirect buff she WILL take the front stage again with a buff, and I'm not sure that's what anyone wants considering Kai'Sa has been dominating pro play for the last two years (not to mention that I know several people complain about her burst/mobility and think that she's unhealthy game design in general).
If you really want to buff Kai'Sa, my opinion is that the best way to do it is through maintaining her three core weaknesses (laning, evolve access, and evolve tradeoffs) while giving her slightly more power either in the late game through her passive or through some additional attack speed per level. Also, please for the love of god round her base mana up to 345 - As someone with OCD, this hurts to look at.