Hello compatriots of Mobafire!

Have you ever wanted to know how to do insane amounts of damage to the enemy team and practically delete them using your skill, mechanics, and teamwork?

You're in the wrong place then because Katarina isn't a very much skill and she isn't mechanically demanding. She requires quick reflexes and a team that can deal at least some level of harassment and poke damage before she can initiate.

I recognize that this guide isn't terribly in-depth but I'm hoping to keep expanding it as I try new things and if you have anything that you feel is missing and important you can feel free to leave a comment on it.

Pros:

Safe laning phase against almost anyone
VERY high damage to groups
strong mid to late game
potential global presence
can one-shot teams

Cons:

Can have a hard laning phase
Needs to snowball before late game
heavily countered by CC
can have trouble one-shoting people

What should I take for summoner spells?

Well, generally I suggest Ignite and Flash because it gives you an extra escape and more damage in lane to help snowball.

You can take Exhaust if you know you're going to have to delete tanks or Cleanse if you can see a lot of CC coming your way but these aren't optimal in most scenarios and I've never really needed them myself.

The item builds should be fairly straight forward. We're looking to maximize our early game presence with high damage because we only get one skill rotation before we're going to get really hurt.

Luden's Tempest
Luden's echo is a strong first item on Katarina. It makes our Bouncing Blade deal more damage while poking and gives us a fairly large damage boost to our combo as a whole making it a VERY strong laning item.

Luden's also gives movement speed which greatly improves our ability to roam.

Rabadon's Deathcap
Rabadon's is by far the strongest AP item in the game and is a must have on any truly full AP champion. However, for this power you get a fairly steep price because of its passive %AP boost. Thus, we get it second to increase the power of our first item which was either Luden's Tempest or Mejai's Soulstealer

Sorcerer's Shoes
These are by far the best option on a deletion machine like Katarina because they give you enough magic pen to cut through 1/2 to 1/3 or the opponents lvl 1 magic resist. If you can finish these second or third then you'll see very good results against anyone not building additional MR.

Abyssal Mask
If you're in an AP lane that is pooping all over your face or against a very AP heavy team then you can rush abyssal scepter as your first item to get the resistances and damage increases from the passive

Zhonya's Hourglass, Seeker's Armguard, Cloth Armor
If you're in an AD lane with a Talon, Zed or anyone else AD you'll want to start cloth armor instead of boots. Why? Because unlike AP champions, AD champions have much more constant poke because their builds increase the damage of their auto attacks meaning they can hurt you a lot without waiting for cooldowns.

If this lane match-up continues to be difficult and you're being forced out of lane a lot upgrade your Cloth Armor into a Seeker's Armguard before you work on Luden's Tempest.

If your lane partner can instantly delete you like Zed and Talon once they hit lvl 6 then rush Zhonya's Hourglass first so that you can avoid as much damage as possible and use the armor to lessen the blow of everything else. From here you'd then work into Rabadon's Deathcap for maximum roaming damage.

Rylai's Crystal Scepter
Rylai's gives you several great benefits:
1) You get lots of AP so you do more damage
2) You slow everyone you damage which means easier multi-kills because people can't run from your resets
3) you get health. Granted this isn't incredibly useful but it does give you a bit more time to make flashy plays or stand in your Death Lotus without being killed.

Void Staff
Void staff is INCREDIBLY important to you. So important it is practically a core item. The only time you don't build this is if the enemy team is building literally NO magic resist. If you see any MR on their team. Even it it's just one or two pairs of Mercury's Treads then you buy this item 4th or 5th.

Hextech Gunblade
Gunblade's are very strong on hybrid champions like Akali, Jax and Kayle. Technically, you are hybrid as two of your abilities; sinister steel and Death Lotus do have AD scaling in them. However, this item still doesn't create as high an impact as strong AP items do.

Gunblade can still be useful however because of its active and the sustain it gives you while you're in your combo. This means that against tanky teams you can survive even if you didn't kill anyone with your combo.

Liandry's Torment
Liandry's isn't a very strong pickup on Katarina. It does give you decent AP, more magic penetration and a passive that works wonders with the Rylai's Crystal Scepter but it doesn't increase our insta-kill potential so I'd only recommend picking this up if the enemy team is really tanky.

Banshee's Veil
Banshee's is great if you're having a ridiculous time avoiding CC. Normally you can just wait out cc like Nautilus's Depth Charge or Annie's stun but sometimes there's just too much to wait for and you need to be protected from it before you find yourself paralyzed in the middle of an angry mob.

Morellonomicon and Athene's Unholy Grail
Why would you even think about getting these on Katarina? She doesn't need CDR because she gets resets. She doesn't even use mana and she can already inflict grievous wounds with her Death Lotus.

RANK 1
Bouncing Blade are our primary poke and harass tool in lane and have the ability to proc damage twice (AKA q + aa = Thunderlord's Decree ) so we take this first and spam it because we don't have mana.

RANK 2
Shunpo is our escape and engage. Jumping to a dagger will also allow us to proc our Thunderlord's Decree to help with trading in lane.

RANK 3
Preparation can be taken earlier if you need to get out of trouble early with the move speed. If not, then it is taken 3rd to allow us to place double daggers.

RANK 6
Death Lotus... it's our ultimate...

Hello laning phase.

This is where we begin to define how this game is going to go. We need to make smart decisions and know our limitations just like with any champion in league of legends. In order to help us make smart decisions we can break up the laning phase into various functions that we will prioritize to increase our effectiveness while concentrating of the fewest possible variables.

Priority 1: Don't die
This doesn't mean that you shouldn't try and kill your opponent but it means that you shouldn't over stay in your lane. You aren't the strongest laner in the game. Don't try to be and recognize that basing early to regen health and miss out on a wave is better than surrendering that same wave and 300 gold to your opponent.

Priority 2: Farming
This is one of the most important thing you can do in the laning phase . Farming well means more money and more money means bigger items with which to delete your opponents.

Don't be suicidal while farming. But learn to farm efficiently.

Priority 3: Poke
This is the third most important thing you can do in the laning phase. You have Bouncing Blade and Thunderlord's Decree and no mana so spam them on your opponent as much as possible. Even if you can't land kills, if you push them out of lane you're free to roam or push your lane which will give you an experience and gold lead.

Priority 4: Dodge
Dodge their skill shots and poke as much as you can. You have your Shunpo which is basically a targeted flash to dodge skill shots with minions or daggers.

Priority 5: Kill
Ok, so priority 4 and 5 are pretty much equal. you can either all-in your lane opponent and kill them with your full combo or if you've successfully completed priority 3 and poked them out of lane you can roam to another lane and kill people there or force them out of lane to give your other lanes an advantage.

When you're trying to go for kills in groups you have two things to consider.
1) who's here that isn't a tank. You'd rather jump on them
2) who's here that isn't at full health. Even a snowballed Katarina can have difficulty one-shoting a full health squishy. Especially if they have a dash or flash to get out of the way.

Combo is pretty straight forward.

To poke in lane: Bouncing Blade - sinsiter steel - Thunderlord's Decree

All-in: Bouncing Blade - Shunpo - sinister steel - Death Lotus - Ignite if necessary.

All-in against a group: Bouncing Blade - pause for blades to bounce to all targets - Shunpo to the easiest to kill target - sinister steel - Death Lotus - get resets and repeat

You're Katarina you don't need a lot of good communication or flashy plays to be successful. All you need is a decent team with engage or poke potential so that you can get resets off of a low health member of the enemy team. Even if you're behind, you can still do a lot of damage on clean up duty as the enemy team is trying to disengage.