When are people going to stop whining about this champ everyday? Katarina might be strong right now, but there are WAY stronger characters in the game right now sitting at WAY higher winrates with WAY easier playstyles. Sure some of the items on her right now might make her a bit powerful, but they're successively tuning them down as time goes and all her core items are being targeted for nerfs next patch, remember it's still Preseason.

Kat is always going to a pain in the ass to face if you don't know how to manage her due to the fact that she's mainly played by one-tricks, in fact that's the nature of most of the one-trick champs in the game (Azir, Irelia, Yasuo etc.). It honestly doesn't take much to learn how to prevent these champs from snowballing out of control in your games, even though it might be a bit trickier in certain scenarios (ex. in a solo-queue environment).