I started to play Kat after I began to get bored of playing Vladimir, and realized quickly that I may have been in love with her. I'm not gonna say that she is probably the best champion in the game, because she isn't, but she is probably, by far, my favorite champion.

**Update** Fixed a stupid mistake I made (in the mastery trees) in the wee hours of the morning.

Pros

- Her W ability, Killer Instincts, is 1, a Passive that deals increased damage; and 2, an active that gives either your Q or your E an extra ability. For Bouncing blade, a healing debuff, and Shunpo, a buff that decreases damage done to you for a few seconds.
- It's really easy to harrass early game with your Bouncing Blades, although it doesn't do much damage, and you can get a lot of last hits with it as well.
- The Shunpo AP conversion rate is really high, making it do a lot of damage late game with the Void Staff and Magic Pen runes.
- Death Lotus can dish out massive amounts of damage on a single target, especially when combined with Ignite. (Its gotten me early kills many times)
- Her passive allows her Death Lotus to be used twice in a team fight if you live long enough

Cons

- More effective Mid-Late game than Early game (not really that bad of a con though)
- Shunpo can sometimes overextend if used on a minion, causing you to go low on health or even get killed, so use it with caution
- Kat is just squishy in general
- Death Lotus can often end in a kill, double, and rarely a triple or quadra (if your lucky and get the kills) with Q/E/R combos - but it is also liable for you to get targeted and burned down easier since you are just sitting there spinning.
- Kat seems to get focused A LOT if shes built.

For runes, I go for the ones that are more effective at the late levels, as you can see by the AP/Level and CDR/Level

Other than those two and Magic Pen for Marks, there's not much more to explain.

Magic Pen since she is AP based, AP..well if you dont know why... and CDR for more rediculous cooldowns than she already gets.

For Quintessences I use the flat AP, just for that extra bit to help early game.

Aaah Masteries...

Anyway, I don't go into any specific mastery for summoner spells, mainly because everybody has their own playstyle and can figure it out for themselves whether or not they want to spec into improved summoner spells.

You can change them however you want, I can't force you to choose these specific masteries, but I do suggest you stay with a 9/21/0, or something close to that. The Offensive mastery gives you Archmage's Savvy for the extra AP, Sorcery for even more Cooldown Reduction, and an extra 15% magic pen from Archaic Knowledge (along with that random point in Deadliness so you can get down past the first tier).

The Defensive Mastery is where all the good stuff is at for Kat. Resistance and Hardiness for a little bit of extra survivability from Armor and Magic Resist, extra health regen from Strength of Spirit, a bit of Dodge to get you past one of the lower tiers, Harden Skin to...well...harden your skin and decrease damage, Veteran's Scars for increased HP, Ardor mainly for increased AP and not so much the increased Attack Speed, and finally Tenacity for the decreased % of damage.

Start out by getting your first rank in Bouncing Blade. It's nice for last hitting the occasional minion when you cant run in and smack him, and getting the occasional harassment on the enemy champions. When you hit level two, go with Shunpo but be careful with it. You can go for that minion with a tiny bit of health when your Blade is on CD and end up in between their melee minions and their ranged minions, which could spell disaster for you if they get lucky in their positioning. At level six you should have 2 ranks in both your Q and E, one in W and one in your ulti. After this, just go straight out Shunpo until its maxed. By the time you are level nine with five ranks in Shunpo, you can be dealing a nice bit of damage to your opponents. After getting your third rank in Bouncing Blades, throw a rank into Survival instincts for the increased damage and a little bit less cooldown on it, then continue to max out Q. After your Q is maxed there's only one skill you can put your remaining points into, save for your ulti which you should max out ASAP anyway...

Now! Onto the Items. To start out with get your Boots and a couple health pots. I see most people get three instead of two, but I like the extra 45g you save...it seems like you can get built quicker...maybe its just me.

When you go B for the first time, get a Kage's Lucky Pick for the AP and extra gold per 5 seconds. I have experimented with this build and getting a Lucky Pick seems to almost double the speed at which you can build at, and I'm sure it can speed up other builds as well.

After the Pick, build towards your Hextech Revolver. The increased spell vamp is almost a necessity to do more and more damage with your Shunpo, and your Death Lotus. I build a Pick because, even though I probably should last hit more, I tend to focus more on harassment with my Bouncing Blade rather than last hitting minions, and because of that, the increased gold generation helps get built faster.

I wait a decent amount of time to get boots. If you don't like it you can change it up a little bit and get them after the lucky pick, but all I noticed was that I did a little bit less damage without the spell vamp from the Hextech Revolver.

Here is where you can begin to differ in your item build. I usually go straight towards my deathcap by buying the Blasting Wand and the Needlessly Large Rod. Sometimes I'll go straight for the Deathcap and skip the Abyssal Scepter, sometimes I'll get my Abyssal Scepter even before the Needlessly Large Rod. It all depends on the comp you are facing. Which brings me to my next point. If I need armor more than Magic Resist, I'll build into Zhonya's Hourglass before the Scepter. Somebody once told me that Hourglass isnt that great for Kat, and I beg to differ. It's 100 AP, 50 Armor, and 2 seconds of invulnerability that can save your *** quite a bit.

Regardless of which sequence you build, go towards the Deathcap if you haven't already. 140 AP and 30% increased AP is awesome for whichever AP toon you are playing.

If you are still playing and have enough money, start building towards the Void Staff. I say this because a lot of the time, whenever I get to building my Void Staff, we are either defending our base for our lives, or already on their Nexus towers.

If you have gotten quite a bit of kills or a ****load of assist, you can sell your Pick (if you havent for any other item already), or if you have the money, build either Will of the Ancients or the Gunblade. If you dont have an AP toon that will benifit from it (such as Annie or Lux) then I would go to Gunblade. It does a % of the enemies current health, and gives you a decent amount of AP

This should be the end of your build.

This build is based loosely upon wRAthoFVuLK's build, Your AP Katarina Du Couteau Resource (dont play with knives), so Props to him with making such an awesome guide. I started out using his guide but soon made alterations to it that you can clearly see. The Rylai's is smart if you dont wanna have to fight people for Red buff or waste your time with it though.