Mistakes every Katarina makes constantly:
HP Shard-
The HP Shard is something that is just better for Katarina every single time. People that debate this are generally unaware of the basic math involved, how mix and true damage comes into play, and also typical values associated with each one. They also just tend to ignore HP scales better. The TL;DR is that:
At level 1, the HP Shard is 25eHP stronger. 25eHP is not typical HP, after hitting mitigation, this is about 15 actual HP. The Armor Shard is better than HP Shard at level 1 by like 15 hp.
At level 2, the Armor Shard is better by about 15eHP, or 7~ HP stronger.
At level 3 they're even.
However these values are entirely ignoring Mix and True damage and these examples are exclusively Physical Damage. If you're in a battle with someone, and they pop ignite on you, this automatically defaults the HP Shard as a better choice. If you're fighting Zed, and he lands his Magic Damage passive on you, HP is automatically a better choice. This is because the range Armor was "better" was never significant, and the moment you take mix or true damage it's entirely worth less than HP, despite HP scaling.
If you're hit with as little as Cheap Shot, you fucked up taking armor.
Average Armor/MR shard enjoyer:
"I never get hit with more than one damage type the entire time. My enemies never kill redbuff or take smite, enemies do not build rageblade, statik, witts, collector, riftmaker, RFC, supports do not land abilities on me, and I win every game before level 4. Enemy mages never land autos on me,(no one lands autos when I go MR) and every laner i fight is talon. I never need to sell refillable and I've also never been ignited(ever). And this is all so I'm at max 20 ehp stronger than HP level 1. I don't need free scaling. I live on the edge. Do you know how valuable 20 ehp is early game noob?"
The answer is that it is not very valuable. You should literally always take HP.
If Armor is that important, you should take HP+Armor and drop 9AP.
This is because 'Math'.
Mejai-
Mejai is an item used to adjust income. This is heavily misunderstood by the large majority of Katarina players, you use this item when you suck at farming, not when you're popping off killstreaks(thats fine too though). It scales as you do (worse). This might sound confusing, so let me explain:
Katarina is a champion that simply has thresholds of damage. Casually explained, her mechanics is not the skillset, collecting gold is. When KatEvolved combos someone, they die because of his excessive income, he does not push QEW better than you most of the time, what happens is his target dies because he farms well, and your target lives because you don't. He gets a reset and looks cool, you don't and die and look like a loser.
The issue isn't Mechanics, it's Income, and so you need to build Mejai.
You simply fall too far behind Katarina's natural curve the moment you farmed stupidly, and you need to supplement it with extra income to look normal.
The logic behind this is how CS works; the average of a CS is valued at 21.75g, if you take this number times your CS score, it will often be very close to how much gold you gained that game from CS. This is also exactly how much 1AP is worth, and so each CS itself averaged out, is worth 1AP for the majority of early game.
This conversion is nice for looking at Mejai, because that means a (kill) being worth 4 stacks, is worth 20AP, or 20 minions (3 waves and change) at base.
3 Waves is incredibly a lot of CS for a takedown when someone is missing CS, but the calculation doesn't actually end there, because this 3 waves of immediate CS is going to be comparable to your income valued against perfectly CSing. 100% CS. And so the idea a kill is worth 3 waves is actually based around the idea you're scoring 12.5 CS per minute. That is not reasonable!
If we half the CS per minute and takedown rate to 50%, that is 6.25 CS per minute, a much more reasonable Katarina income, making the 4 stacks of a kill worth actually almost 7 waves of income.
But we don't have to stop there, because I know many of you noobs do not get 6.25csm average.
If we look at the lowest of the low, a player like SomeKat gets 27% last hits, this means that when SomeKat gets a takedown with 3 cs per minute, this is comparable to if SomeKat had sat in lane and farmed 14 waves.
If you are getting 3cs per minute like garbage SomeKat, then it is no longer your incentive to actually stay in lane. You suck at lane. You need to build a Mejai, and score a single kill for the equivalent of 14 waves of gold. You will never "CS better" than buying Mejai the moment you miss ANY farm. You have to farm like Faker to not justify this item, and many of you do not.
Rocketbelt into lots of Melee and MR items-
This is so cringe. Rocketbelt is not Katarina's main item you idiots. Magic Pen is the most potent stat in the game, but it comes with conditionals. If the following is true, Magic Pen is the best stat you can buy:
- The enemies are predominantly Ranged auto attacks.
- The enemies do not have MR Items, and probably will not buy MR Items.
As long as these two things are true, Rocketbelt is absolutely one of her best possible items.
As soon as either of these things are not true, Rocketbelt is pretty trash.
This really isn't that hard to explain, Penetration has diminished returns as you penetrate greater amounts of armor, and also if you fail to penetrate the entire thing. This makes targets with less natural MR(Ranged units) more appealing to build Magic Pen against in the first place.
If the enemies build a Null Magic Mantle, being ranged will no longer make a difference, and magic pen will be much more garbage.
This is honestly like entirely basic statistical stuff, every katarina should know this, most of you don't anyway.
Buy Pen against Squishies ONLY.
Using Start items other than Seal and Longsword-
Dorans Shield is trash if you're not a challenger farmer, you're literally just going to put yourself farther behind delaying Seal or having had pressure with longsword.
Borrowing some of the Mejai math from above, purchasing a shield puts you behind 20 minions, or 3 waves, or potentially 6 waves if you land 50% last hits. Buying this shield is not worth putting you behind up to 6 waves or more, ever, and this is in comparison to a Longsword that you (will) sell, returning you 11 minions(2 waves, up to 4).
If you compare the income of two people at 50% last hit, the person that buys the longsword and sells it, is literally 10 waves of income ahead of the person that sits on their shield 'for CS'.
TL;DR the shield puts you behind by an amount it can never recover, this alone is obvious to why you should not use it. It also delays Mejai and lowers kill pressure into negatives. Dorans sword is even more stupid than this. You can pretty easily just stop using these items. Thx.
Maxing Abilities-
Most of you just blatantly mindlessly max Q, this is also not as efficient as many other possible options. Katarina is a combo champion, and can benefit from having both points of Q AND E, so that more of her combos are practically available. I'm not going to tell you to do anything specific, just that you should probably attempt to learn how to play not just maxing Q.