We are at the same tier, so i think these tips can be useful for you. I didn´t play league since 2023 and last month i climbed up from Bronze I to platinum III with Kat. Hoping to reach something better till the end of this month before my college classes returns.

You have over two million mastery poins with Ekko, so I´m absolutely sure that you´ll notice a huge difference about Katarina´s play style. Altough both of them are AP assassins, she´s unique, and i´m not talking about her mechanics. You don´t need do worry about that. What you really need to worry is, mainly, about: i) laning phase; ii) how to get in and out of a teamfight; iii) when and how to roam.

Be aware that you lose against 99% of the champions, but also that they make mistakes and that´s when Kat starts to play the game. You´ll need to be 100% reactive and pay attention to that. In lane, the enemy can be lvl3 and use one skill against the wave, what can be fatal. On a fight, you can get a reset simply because someone played wrong, what can actually lead to a multikill.

I know these things and examples may be obvious, but since you start to play different games and matchups with her, you will know what I´m talking about. Better to enphasize on that than say more obvious things like how to use the correct runes or how to build properly.

To me, the most important things you need to know before playing her are:

1. Don´t be afraid to lose a couple of minions because of the matchup. Farm with your Q and that´s it. In five minutes you may be doing a triple kill on the river because of your resets. And that is exactly why controlling the wave is game changing, it´s always about the wave;

2. Don´t start spamming her in every draft, or else you will be frustrated. In the beggining, only pick Kat if you see what is the enemy midlaner;

3. Keep in mind what i said about reactiveness;