This is my build for Katarina, I've been playing her lately and been getting awesome scores, even when the game is lost. This is a AP build for Katarina. This build I use for when I play mid, that's why I max. Bouncing Blade first before Shunpo for harassing them as much as possible. If you play side-lane, max. Shunpo first and then Bouncing Blade.

THIS BUILD IS STILL BEING EDITED SO IT'S NOT FINISHED YET.

Pro's:
- Huge damage output
- Her passive is just overpowered in teamfights
- Great ganker with Shunpo
- Dominant on mid with Bouncing Blade's

Cons:
- Can be Crowd Controlled easily
- Is being focused first mostly couse of her huge damage output

Like I said before, I use this Skill Sequence for MID-Lane, thats why I maximize Bouncing Blade first, for harassing the mid champ as much as possible. If you go side-lane just maximize Shunpo first for huge damage on enemy champions. In Teamfights you want to use Killer Instincts with Shunpo, becouse this will reduce incoming damage wich is very neccesery becouse mostly you will be focused since of your huge damage output.

My summoner spells are: Flash & Ignite.

Flash:
This SS speaks for itself, it's great for chasing or escaping from enemy champions or in teamfights. It's also a great combo with Shunpo to get to the enemy champion very quickly and easy.

Ignite:
This is another SS that speaks for itself, in teamfights you wanna use this on the tanks to burn them down quickly. Also very usefull for when the enemy escapes with very low health and you can't get in close range to kill him yourself, just watch him burn to death by your Ignite.

Dorans Shield: This is the first item you want to buy, for extra Health and Health Regen.

Sorcerers Boots: This is the second item you want to get, for extra movement speed and Magic Penetration.

Mejai's Soulstealer: This will be your best item if you get some kills, you wanna try to die as less as possible with this item couse then you will lose very valiable stacks.

Rylai's Crystal Scepter: This will help you alot, by the extra HP you will get, extra AP and do not forget it's passive, to slow enemies with your spells. This item will be very good for chasing enemy champions.

Rabadon's Deathcap: I don't really need to explain this item, do I?

Abyssal Scepter: Very good in teamfights also couse this item will reduce every enemies Magic Resistance in close range.

Void Staff: Your last item if the game is still going on. For this item you need to sell Dorans Shield obviously. This item is good to kill enemy champions easier becouse of it's Magic Penetration.