Kat is not "OP" or "broken" she is simply situational.
Look I have been playing kat since early season 4. Ive made it to gold 1 with her and I find that katarina is in fact not broken. Simply good and horrible in certain match ups. I feel that I need to address this since everyone sees people penta kill an entire team and suddenly they are op. This in simple terms is entirely untrue. I may or may not be the most qualified to say but I like to think that im not a total imbecile when it comes to kat at least. So heres why shes not broken or "op". Firstly the amount of decent match ups against her are few. Shes countered by very good champions in this season like for example yasuo. Fizz is hard, lulu, fiddle sticks, zed, kayle, talon, and the list goes on and on.
Especially in high elos you not only have to know kat, you have to know the enemy's champion as well or you will lose. (supposing they are good). Some of her easier match ups are Ekko and veigar (early game). But otherwise laning is terrible. That and her base health and regen were nerfed too so instead of like 620 hp lvl 1 she has like 540 base I think now or something like that. Her laning is not good. So thats one way shes not OP because I see it as if you have an op champ shouldnt they only be considered op if they are good in all stages in the game? Another example, not only is it your enemy mid lane its also the whole composition. Poppy now completely shits on kat in team fights because she has a low cool down displacement. Before you lecture me on "timing" I realise that timing is key.
But there are team comps that make it really hard to be immensely useful in team fights. These very situations are what make Kat an un broken or un OP champion. Especially with the introduction of Juggernauts. Items like Steraks Gage completely shut kat up. Now, on to the way Kat can be op (this is where the situational perspective shows up). Katarina as a champion has the potential to snow ball extremely hard. That is fact. But if you put in the things ive mentioned earlier. A bad laning phase can put you behind. heres another example. I as katarina am up against a Zed, I mess up and boom. I die and zed is slightly ahead. I have two options, roam or try to get back ahead through farming.
The latter decision is not a good one. However, oh look its a... nautilus and a... ashe bot lane well that pretty much means unless im there at the right time Im not doing shit and oh look its a.. poppy top. Goody. So not only am I going to have a struggle finding roam opportunity im going to have an even harder team fight. So this comp is shit for kat basically. Just compositions of teams can nullify kat. A good kat can utilize this but sometimes shit happens like the top lane gets ahead and has a few mr items and you cant really do much. She gets more and more ahead and then shes just a machine late game and theres just nothing you can do before your team gets demolished or maybe they dont need to use up all their cc. Maybe they are smart and saving it for you.
Its situations like these that make kat a both skill required champion and a cunning required champion.
Disclaimer. If you get ahead, and you know what you're doing. You can make work and mess them up but not a guarantee. Shes not hard to learn but ill be damned if someone says she easy to master. "Just ult and kill everything" yeah.. right. Good luck with that. Anyways this shit was getting to me so I use the ranting box to fill up this computer screen.
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+ full stax equals bye bye team. Peace lemme hear your thoughts if you took the time to read this.