This guide was originally posted by someone who thought they were on their account (We got that sorted out) and it was, to be blunt, bad. The first comment on here is testament to that.

But since I can't figure out how to get rid of it, I might as well make one for the Katarina I play now.

I'm revising my revision of the build that was based off of my early game style... How irritating. Even my head hurts.

This doesn't mean I'm that interested in the math behind it; Hybrid just rolls smoother for me than AP, and if it contrasts with your own play style, I am not the one who will change your mind, because frankly I don't care how you play it. The only reason I'm doing this is because I'm a bit of a perfectionist and this is a blotch on my page.

Hybrid/AD is, in my opinion, underused and underrated. Almost every Katarina player I come across who plays in the same game as me calls me a noob and then proceeds to get rolled under because they're about as durable as tissue paper, as reinforced with ice (Rylai's) as it may be.

Katarina in general:
+High damage
+Passive makes for great multikill potential
+Optimally, even defeats healers such as Fiddlesticks with W + Q and outlasts other burst mages with W+E
+Classic snowball
-Fragile
-Easily defeated by repetitive stuns
-You'll usually be the target of damage even if you're not fed.

Look more closely. And add her pros and cons to each list.

AP Katarina
+ Higher Shunpo damage
+ Death Lotus is the showstopper.
+ Higher tower damage
- Once stunned during Death Lotus, the game is over unless your teammates ninja assist you or your pathetic autoattack accidentally kills something.
- Could have tower damage, maybe, if you got Lich Bane and had things to attack for the proc...

AP doesn't really add more options, does it? And since most Katarina players I know don't usually get any sort of spell vamp until far later, they have no viable sustain. (Rylai's does not count as durability. You went from wet paper to dry paper.) But this is the classic pubstomper assassin we all know and love.

AD Katarina
+ Much higher Bouncing Blade damage.
+ Autoattacks are dangerous.
- Shunpo is only a positioning tool.

AD is a little better because even if you only traded a strong Shunpo for a strong(er) Bouncing Blade, you can still rely on autoattacks to hurt people. Unfortunately, for any sort of sustain you'll need Bloodthister or at the very least Hextech Revolver, and you might as well had went hybrid.

Hybrid Katarina
+ Autoattacks deal heavy damage.
+ All spells deal damage adequately.
+ Has tower damage.
- Does not solve any of her weaknesses.

My Build
+ Provides much needed sustain for either style, AD or AP, with Life Steal and Spell Vampirism.
+ Adds CC just as effectively as Rylai's (Gunblade Slow is bigger, too)
- Takes a while to reach the first item.
- You're essentially getting hard stats, with Gunblade being your only utility.

Spell Penetration - SpellPen does not offer that much for me. Getting the full Spell Pen doesn't even break their base resistance, and it certainly won't if they have any kind of masteries/runes to increase their base MR.

Health/Health per level - Less is more. By this I mean the armor protects your precious HPs against physical damage, and you can dodge most magic abilities anyway. And, one would assume their AD whatever would have ArPen runes, so if you got HPs, they're dealing you true damage and still eating away at you just as effectively as otherwise.
(Max ArPen not including inherent skills = 31. My Armor at lv.1 = 37)

CDR/CDR per level - You don't need it. The passive is all you need. And to get it, you're trading 9 AP. Doesn't seem like much, but it's the only boost to AP you're gonna get for a long while.

Spell Pen Marks - This bears a review. Why not these over AD? Because AD is building your Q, and Spell Pen isn't. You take off a marginal about of MR anyway even on full 9, and 8.5 + 3 + 10 (Runes, masteries, DBlade, respectively) adds up.

Assassins were made to be aggressive, in my opinion, and this fits my playstyle for assassins. Also, I am fond of the 3 AD halfway down the line, the 10 AP from ignite, and the 4% extra damage. An extra damage for every 25 damage, if you will. It adds up.

I used to do 9/21/0, but I don't like the defense as much as the offense, especially when my play style relies on my killing them before they attack me excessively. Also, sustain > durability, if for no other reason than to sustain you need to damage more fervently. Carries prove that relentlessly.

Since you don't have mana, mana regen is a moot point, and I want to have crazy beginner stats. So I got a DBlade (Even though the life steal is just as worthless as the mana regen) and a second one after my first kill to ensure I could keep my advantage. Sorcerer's Shoes for damage increase, then I rush a Gunblade (Revolver if more Shunpo, Cutlass if more Bouncing Blade) and have arguably the strongest burst in the game short of LeBlanc plus the DPS to beat most AD fighters. (Freakin' Garen is still an issue.)

After Gunblade I usually get The Bloodthirster because my Life Steal is still lacking comparitively, and my Spell Vampirism is fine. Rabadon's could be gotten second, but during this time your autoattack is faltering, and I'm still using it. After Rabadon's I pretty much get whatever I want, countering the enemy team. Thornmail for backdooring and AD champs, Banshee's Veil or Force of Nature (More for the MR/MS than the regen) for AP burst and AoE, more damage to counter increased glass cannon (Can't hit me if you're dead faster than before.)

Even if it's assured I'll get fed, I don't get Mejai's Soulstealer/Sword of the Occult/Leviathan because I just don't like the spirit of these items. I die and it's a dramatic decrease in power.

I don't like it. The passive isn't great and the active is only good for Bouncing Blade for me. I don't get it early because I want more bounces on Bouncing Blade early. I don't get it late because it doesn't serve a purpose then. Although it does have the "She was strong before and now she's dealing more AoE damage..." effect on enemies, which while unproven makes them surrender when you hit lv.13.

Bouncing Blade vs Shunpo
Both are nukes. One moves you behind the enemy, and one hits the enemies next to them. The difference?

You do not harass with a teleport/escape. That's how you get killed. Trade it for a stronger Bouncing Blade and the damage is not wasted waiting for enemies to overextend for a safe jump. And everyone who talks about damage comparisons between AD and AP use Shunpo's raw damage to compare it, and never think or talk about the situations it's used in. I.E. Can't be used unless you're killing someone or escaping, the latter not needing damage to matter.

Above is just what I use. I don't see much point in escape SS as Katarina when I have Shunpo, but there are instances where it failed me because nothing was around to jump to or my lane partner totally just left me in the dust.

Ghost/Exhaust
Survivor kit. Lets you catch fleeing enemies and wussy lane partners you need to jump to in addition to disabling enemies you need to kill/escape from.

Ghost/Ignite
The towerdive kit. Sprint in, catch them running, burst, ignite their sliver of health, and get the hell outta dodge. Also fills the niche my lack of W does not.

Exhaust/Ignite
Slayer kit. Pretty much ensures you killed them and they stayed dead.

Flash/Ghost
Range kit. You won't have to worry about dying this way, unless you really screwed up. And you won't have to worry about catching people, unless you lag.

Flash/Ignite
Dual kit. Same thing as Ghost/Ignite except Flash is better for defense as opposed to catching someone. It's hard to both land Flash and Shunpo onto someone at the same time, since it moves to your cursor and flashes cancel movement.

Flash/Exhaust
Surprise kit. Don't take anything with you that you don't need. Also helps for failed tower dives that they survive, and leave you without an escape.

Rally: Surprisingly effective when you start using Death Lotus. But I don't recommend it. More of a joke.

Teleport: Katarina gets around extremely well, what with Shunpo and having a high base MS (325). Still, if nobody else can defend against the BD champs, might as well.

Revive: Feeder tool. 'nuff said.

Heal: I will leave this entirely up to you. Sacrifice damage for health. Oh, by the way, ignite and you're dead.

I don't do mid. There's not enough people to kill in mid. I like having two lane enemies because they both die easily. And by easily I mean eat the AD carry and their papery support with your superior health pool, defenses, and damage. (On this build you have arguably more AP and AD than anyone else in the game, and more armor if they aren't specialized in it.)

Bouncing Blade harass, or last hit if they're standing back, and Shunpo to dodge close range harass and long range skillshots. Not much you can do against enemies like Gangplank but hit them harder than they hit you, just don't use Shunpo to do it. Since Bouncing Blade has priority and AD boosts in this build, you can harass more effectively than most heroes, especially because you can do it endlessly with no mana. You can also towerdive enemies if a minion wave is nearby even at this stage, since a kill results in Shunpo being reset. Jump in, beat them up, jump out before the tower even fires.

Either you or your partner needs to roam. You can handle anyone short of Caitlyn on harass, and maybe her if you dodge her Peacemaker, and you're better suited to roaming than Alistar because of your ability to reach enemies. Just make sure the one you're ganking for gets there first, or they won't be ready for your speed. If there's no point in roaming (All towers pushed, for example, or no jungler on their team) then just take the tower. They can't hide under it since Bouncing Blade + Shunpo to lane partner/allied minion lets you practically attack them under the tower without being targeted.

Classic assassin game; hang back, wait for a lull, clean house. Duel as many solo people as possible because they probably won't win and can't escape because of your Gunblade, and your BFSword/Bloodthister allows you to even fight off Tryndamere if he isn't fed. Takes some creativity to get around his Rage, though. In teamfights, wait till all stuns are used, even if your team is losing and falling back. Actually, it's technically even better for you if your team is falling back, because the enemies will be so preoccupied with chasing they won't have time to switch from predator mentality to survivor mentality when you jump from nowhere throwing knives all over the place.