This is all fine runes for an AP Katarina.

Q: Why not purchase AP/level runes?
A: These are great to start with, and Katarina wants to get fed as soon as possible :D

Q: Why ?
A These magic penetration runes and Sorcerer's Shoes almost cuts off every champions starting magic resistance

Ranged always mid? hell no, Katarina will beat every midders butt.
Therefore i recomend you to start with a Doran's Shield because of the HP and regen, which increases your endurance to stay in mid.

Later i prefer to buy Giant's Belt because... you'll need HP
Then Blasting Wand and Amplifying Tome. Giant's Belt + Blasting Wand + Amplifying Tome -> Rylai's Crystal Scepter

If your score looks good, then Mejai's Soulstealer is an obvious choice.

Afterwards you will start building up your Hextech Gunblade. Starting with Bilgewater Cutlass it has a great ability if your abilities are on CD.

Late game you might need Abyssal Mask because your enemies are stacking Magic Resistance (If they'r clever enough)

Ending game:
Now you should choose - Rabandon's Deathcap or Zhonya’s Housglass.
Rabandon's Deathcap is great cus of the extra AP
Zhonya’s Housglass is also a great item. Because in the end of the game your enemies learn to focus you in teamfights, so the 2 seconds of invulnerability is pricesless.

ROFLMAO
This Passive is just great, Jump in a teamfight -> Deathlotus get 4 kills/assists and you Deathlotus is all ready again + your bag is now 100 gold heavier.



Cost: Nothing
Cooldown: 8 seconds
Damage: 20/40/60/80/100
You want to max this ability as soon as possible. It's great for laning, and it's realy annoying for your opponents. You can hit a minion beside a hero and it will hit the hero as well.
Note: This deals magic damage


Cost: Nothing
Cooldown: 22/20/18/16/14 seconds
Bonus damage: 8/12/16/20/24
Damage redution for : 15/20/25/30/35
This is has a great synergy with Shunpo because of the damage reduction. Pop Killer Instinct's and engage with Shunpo -> Deathlotus
And the Healing is great against healing/lifestealing heroes such as Soraka, Dr. Mundo etc.


Cost: Nothing
Cooldown: 10/9/8/7/6 seconds
Damage: 90/120/150/180/210 + 0,75*AP
You can use this not only to engage with but also to escape, and in the end it will deal a huge amount of damage as your AP increases.
Note: This deals magic damage



Cost: Nothing
Cooldown: 60 seconds
Damage for each dagger: 50/65/80 + 0,55*AD or 0,3*AP
Death Lotus chooses either AP or AD depending on which one you got the highes stats, therefore it's great to focus on just one of them (AD or AP).
You will channel this ability, therefore it's easy to interrupt with any form of immobilty such as fear, stun, suppresion etc.
Note: This deals magic damage

In my opinion flash is a must have for escaping/engaging

Exhaust - i realy like the Flash -> Exhaust -> Death Lotus combination

As the game continues and you wil get you Rylai's Crystal Scepter you won't real need Exhaust for the combo above, because whenever a blade from Death Lotus will hit the target, he will also gets slowed. Therefore you can switch Exhaust for Ignite if you feel you need some extra damage

When you got AP with Katarina, it means you are dependent on you ablities, therefore you want alot of CD reduction.
CD reduction -> 9/0/21
And as Katarina you want to be mid for the extra gold and Experience, so you can gank early game. That's why you want 4 points in Awareness and a point in Greed .

You get extra AP, Magic Penetration, CD reduction and an improved exhaust from your offense tree for just 9 points. DEAL!

You should wait 3 seconds to join a teamfight for one reason.
The enemies learn to focus you, whenever you use Death Lotus, so if you engage later than the rest of the team you might get some kills and have a minor chance of dieng.

Galio + Katarina = OWNAGE
And why is that?
Well take a look at Galio ulti - Idol of Durand. Galio flashes in a bunch of enemies using Idol of Durand , then you will come right after using Death Lotus and boom. Easy ****.

Here you see an example of that very combo - not the best example but.. Play Video /league-of-legends/champion/galio-57