This is a guide on how I play Katarina; 100% AP power, the way she should be played. The days of AD Katarina are gone, and I find it to be inferior to AP. I also find Hybrid Kata to be inferior. Please comment and tell me what you think!

Flat yellow health runes for early survivability, all else goes in flat AP. You will need a decent amount early on to dish out massive damage even at lvl 3. The earlier Kata gets her kills, the more difficult she becomes to bring down.

Max out all AP-related masteries in the offense tree, and spec down to XP boost in Utility. Being a step ahead of the enemy is never a bad idea. Perseverence also gives you a little health regen boost, allowing you to stay in the lane as long as possible.

Start out with your Boots of Speed, as well as 3 health potions. Kata is quite frail early game, so they allow you to take a few hits more than you would otherwise. If you are doing well, go for Mejai's next. If not, you should start building your Rylai's. The slow effect is vital for Katarina. Enemies being slowed while you fling a billion daggers at them? Oh yes. After that, start heading towards double-Rabadon. If you manage to get these, the enemies will have a hard time dealing with your Shunpo-Ulti combo. Last item should be Zhonya's Hourglass, for even MORE ability power and added survivability, which comes in VERY handy that late in the game.

Put a rank bouncing blade at lvl 1, and keep it there for now. It will serve as a skill for last-hitting minions in the lane. Shunpo is your bread and butter skill, so max it out first. Grab Killer Instincts at lvl 4, and ulti whenever possible. When shunpo is maxed out, max out Bouncing Blades, and skill up Killer Instincts last.

Exhaust-Ignite combo helps out immensively early game. Once you reach lvl 6, shunpo in, exhaust, use ulti and ignite. They will most likely end up dead. Exhaust also helps for escaping, and for stopping brawlers like Tryndamere and other auto-attack champions from killing you while you fling daggers in their faces.

Pros
* Lots of damage starting early on.
* Great escape mechanic - Shunpo. It also deals massive damage, and scales very well with AP
* One of the best Ultis in the game, in my honest opinion. One of those that are likely to score you a pentakill. It tears up enemies in team fights.

Cons
- Useless if silenced, or CC'd.
- If she does bad early game, she has issues later in the game.

If you're doing things right, you should be killing things left and right with your W-E-R combo (Killer Instics-Shunpo-Death Lotus) starting early on. Good luck and have mercy upon those that meet you, the dreaded AP Kata!