Katarina's Teamfighting Pressure Needs To Be Toned Down.

So you've got a mid lane, highly mobile, fully offensive (all 4 abilities do damage, giving her high burst), capable of being on par with and even better than most mid lane mages, but to take it a step further she's the easiest champion to pentakill with and escape alive in the game.

Her biggest issue is that you can shut her down, beat her into 5 deaths and 0 kills, harass her and take her to half the CS most champions have, and she will still get a pentakill. She's mobile enough to avoid some focus, and Zhonya's is what makes her absolutely overpowered in teamfights. Every other good teamfighting, high burst champion has some fatal flaw. Huge mana costs or cooldown, no mobility, etc. Her passive needs a cap or shrinking effect. There's no reason we should lose the game after having a huge lead just because Katarina swoops in and feeds after she had been outplayed the entire game. This season even encourages teamfights so you either ban Katarina or lose every important objective because she's waiting to get a pentakill.

Don't touch her AP ratios, don't touch her 1v1 capabilities. Do something about her ability to pentakill in a matter of seconds. There are 2 items that allow her to cheat death, and on top of that she has shunpo.