Hello. Today I am creating my first guide. Please, support it :) In this guide i will show how i play katarina and own middle. Using this guide u will be able to destroy AP champions like Annie and Lux.

Pros:

• Great burst damage.
• Multiple targeted ultimate.
• No mana, u can spam spells as much as u want
• Amazing mobility.

Cons:

• Squishy.
• Targeted in team fights
• Ultimate can be cancelled by any stun, pull or knock.
• No cc at all...

Greater Quintessence of Ability Power will help u deal more damage with abilities at early game.
Greater Mark of Magic Penetration will allow u to kill enemies, who has mag. ressist, faster.
Greater Seal of Armor will give u armor, who makes u less squishy at early game.
Greater Glyph of Scaling Ability Power will give u much of ability power at late game

gives u early ap and it also allows u to fast bulid Mejai's Soulstealer
why those? well it allows u to come back into your lane and be faster in fight. It makes ur mobility even better. Also, it allows u to reduce the distance between u and chased oppoent so u can Shunpo on him.
Gives u HP, who makes u not so squishy anymore and gives u your only cc. Your slowing Shunpo and slowing Death Lotus makes u inescapable.
gives u lots of AP. If u have at least 10 mejai stacks at this point, u can call urself fed :)
this item gives u ap, atack damage, spell wamp and life steal. It allows u to farm faster and get lots of health from minions.
gives u armor, lots of AP and amazing ability = stasis.
After finishing your bulid, u dont have where to put ur gold so buy arr elexirs.

Upgrade Bouncing Blades first. Its your ranged atack. Each upgrade allows blade to bounce one more time. Its perfect farming ability. Also, it deals main damage early game. By the way, Shunpo combined with some AP deals damage even if its not upgraded. Upgrade Shunpo second.
And upgrade Preparation later. Ultimate like all ultimates..

is one of the best chose. u have to get it.
i also recomend it. I dont recommend other spells :)

In early game, try to peform Bouncing Blades on minions with low HP to finish them. Also allow bounce to go on your opponent. As soon as you collect enough money for Mejai's Soulstealer, go get it. If u see that u can Shunpo your oppnent, do it only when he isnt standing near lots of his minions, cuz it will damage u hard. After Shunpo land some basic atacks and when he gets a little away trow Bouncing Blades. If he is low HP, use ignite.. If he is much hp, get away as soon as possible. Once u hit lvl 6, u can start ganking. Also u can kill ur opponent with yout ultimate. Just land it perfectly.. Beware of AD champions such as Caitlyn or Draven, they can beat u easy..
Also, in early game, if u have low hp and ur opponent has more but low either, and if he is ready to go back when u try to reduce distance to Shunpo, u can peform surprise atack. All u need to do is to Flash into him and imedialty Shunpo him. Make sure ur Flash makes u able to peform imediate Shunpo. If ur opponent is still alive, use Bouncing Blades on him

This is it. Enjoy your middle destruction and good luck. I hope u rate it good :)