A way to increase Cassiopeia's winrate by at least 3% in the hotfix without buffing her numbers

Put "Catalyst of the Aeons" in the "early items" or "essential items" section of her recommended items page.

Catalyst + Twin Fangs basically gives her a free health potion every two waves before we even get into further health and mana benefits gained whenever she is doing anything but last hitting, no champion comes close to abusing it as hard as she does.

The "most popular" and "highest winrate" builds on champion.gg both completely exclude any item built out of catalyst despite this obvious synergy, yet lolking.net shows Rod of Ages has a higher winrate on Cass than even a completed Seraph's Embrace.

Consider further that Catalyst into Rod of Ages is the item you'd tend to build over tear if you were LOSING the lane as Cassiopeia, meaning that its winrate should be artificially deflated by Cassiopeias who were having a tough time in lane and built the item to try to salvage a losing game (And it worked!), hiding even more of its power on her.

She is great at stacking tear, but Catalyst just works so hard to cover up her major weaknesses in the early game, I think Cass should actually build both those items in the early game despite how long it puts off her AP items just because the sustain is so huge and lets her turbofarm into lategame status while being impossible to push out of lane. Tear is a great use for that gold you were going to spend on Sorc's boots before 6.9 when you had feet to put them on.

I'm not saying this would balance her, but it would definitely give a better picture of her actual power right now because the new Cassiopeia is clearly going to be a champion that abuses Catalyst to turbo-farm and most player haven't figured that out yet.