Hey guys! I'm Simosha, and this is my first ever guide! It's not going to be very in-depth and you won't learn too much, but if you're looking for a build that can win you games and you don't know what to buy in certain situation this can help you out. I want to dedicate this guide to my non-Katarina playing friends: Caopow, Yakodin, Curryadev, LeafWaxer and SilverTipBullet. I tried to make this guide short and simple because that's what I usually look for in a guide since if you're the kind of player that is alright with having a guide with options, you can probably build by yourself. Make sure to upvote and if you're downvoting tell me why! I want to make tons of guides.

For items, make sure to get a Rabadons Deathcap if you're ahead and to get an Abyssal if you're facing hard AP burst (eg. Fizz, Lux, Ahri). If you're really ahead (eg. 2/0 by 6:00 min) you can get a Mejai's Soulstealer although I've never actually tried that myself for some reason.

The Combos:
Farming: Q > W
Harassing: Q > E > W
All In: Q > E > W > R
Jumping into a Teamfight: E > W > R (Don't waste your time with the Q)

Katarina AP Mid:
Pros: High Mobility, Hard to Gank, Best Pentakill Champion in the Game, The Resets, ****s Damage
Cons: Weak Early Laning Phase, Squishy like all AP Assassins (Gragas isn't an assassin), No CC

Katarina is the KS Queen. Use that to your advantage. Take the stress of murder of your teammates health and E > W that Caitlyn with 56hp! What seperates the good Katarinas from the bad Katarinas are the ults. When I play Katarina, I allow my team to poke down the enemies until they are all around 3/4 health and then I initiate unless we have a good tanky initiator (eg. Malphite, Jax) with my ult and get a penta.

Katarina is OP and play her if you want pentas. She does a lot of damage but you need to get used to her jump and kill playstyle. She's my favourite champion because of her high skillcap, damage output and fun.