Why Karthus mid? Because he is awesome lane controller. He needs experience early game. He needs farm. He is carry.

I advise you to take a look at ELO Hell - What it is and how to escape by TheShinWire. Basics of this game. Well, advanced basics.

First of all, who is mr. Karthus?
Death Defied: I can die, if it is nessessary,
Lay Waste: I am AP carry,
Wall of Pain: I have CC,
Defile: I am great farmer,
Requiem: I can cripple or even kill whole enemy team, wherever they are. Your IWINLOL button.

SO: You are an awesome farmer, who can deal lots of area damage. Wall of Pain is a very good area CC. This means that you just shine in teamfights with correct items and good farm. And what makes karthus Karthus, his ultimate.

SPACESPACESPACESPACE

Pros

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Cons

Amazing farmer. One of the best choises, if you want to carry the game. The most global ultimate in game, that makes every enemy shiver in fear. Has CC.

Squishy. Item dependent. Weak in early game. No escape mechanism.

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SPACESPACE

Play Karthus if:

SPACESPACESPACESPACESPA

Don't play Karthus if:

You are an attention ***** enjoy being in the spotlight. You like farming and are good at it. You want to carry the game with not an autoattacker. You want to play the strongest area damage champion. You want your enemies to rage. You play to win.

You prefer to humbly support your teammates to victory. You last hit like my 11 year old cousin with Soraka. Your team has a combination of these champions Then your remaining teammate types "3 carrys? We needingering a tanka to takering damage." then proceeds to pick You hate farming. You are a dumbass. Your teammates are dumbasses. Nothing helps here, though. Only Shen.

First of all you are area damage dealer. Thus 21 in offense. You need 9 in utility to keep blue buff longer, as it gives you cooldown reduction. I hope i don't need to explain every mastery point.

This build is for mid Karthus.

I want to get Requiem as soon as possible to start the enemy team rage cycle (they rage, make mistakes, rage more, mistake more, ect.). You may want to get Requiem early for your own reasons.
Start with Lay Waste because Wall of Pain don't do any damage and Defile costs too much mana. Also Lay Waste has greater range than Defile.

Second point in Defile, to have your mana regaining early, which leads to your lane sustainment.

Lay Waste is your main nuke early game, so Lay Waste> Defile.

Fourth skill point goes to Wall of Pain, your CC. Important in harrasing and when ganks income mid (both your and enemy).

Wall of Pain level 1 is enough, so max out your damage dealing skills first.

Greater Mark of Magic Penetration should be magic penetration, this is solid as a rock.
CAUTION MATH INCOMING
Damage dealt to enemies counts like that:
Real magic damage = magic damage dealt*(100/(100+magic resist))
Example: 100 magic resist decreases magic damage taken by 50%
All champions start with 30 - 60 magic resist (60 can be reached with runes and masteries).
9 marks give you 0.95*9 = 8.55 magic penetration.
How magic penetration works?
It decreases magic resist by your magic penetration.
Example: you attack enemy with Lay Waste level 5, who has 30 magic resist. Damage from Lay Waste is 240. 240*100/(100+30)=184,61...=185
Now if you have your marks, this will be 240*100/(100+21,45)=197,61...=198
Pretty low benefit, you say?
But what happens, when you have your sorcerer shoes?
Without marks: 240*100/(100+10)=218,18...=218
With marks: 240*100/(100+1,45)=236,56...=237
This is better even than AP per level marks. They give you 1.8*9=16,2 AP at level 18, and Lay Waste scales AP only with 0,6 modificator.

Greater Seal of Scaling Mana Regeneration gives you very good mana regeneration, which is very important because in my guide I use no Tear of the Goddess.

Greater Glyph of Scaling Ability Power just AP.

Greater Quintessence of Ability Power just more early AP. 4,95*3 AP gives you +8,91 damage on Lay Waste.

I actually don't care much about runes. They help a lot when you are facing a mirror lane. In other cases you just okay with having them, if they are not ******ed on your champion.

Flash is a must. You need escape mechanism.
Teleport is the best choise for solo mid champion. You can go back any time, heal, regenerate mana, buy items, and get back to lane.
Also not bad choises are:
Ghost
Heal
Ignite
If you jungle:
Smite

Starting items should be
1. Sapphire Crystal + Health Potion + Health Potion
or
2. Boots + Health Potion + Health Potion + Health Potion.
1 is standart. 2 is against skillshot champions, or other Karthus or Cassiopeia.


Sorcerer's Shoes vs Ionian Boots of Lucidity
Face it. Only skill that really benefits from Ionian Boots of Lucidity is Lay Waste.
Other skills are used once per teamfight, and Defile is toggle on skill.
On the other hand, Sorcerer's Shoes amplifies all your magic damage.
If you need cooldown reduction, get blue buff.

Rod of Ages? This item provides you mana, ability power, health. Without this health, you won't have enough time to activate your Zhonya's Hourglass - they will nuke you faster.

Rabadon's Deathcap? Yes.

Will of the Ancients? You are AP carry. You can constantly spam magic damage. Ideal substance for Will of the Ancients.

Zhonya's Hourglass? Neat trick. You have toggle on skill - Defile. When you are dying, with activated Defile turn Zhonya's Hourglass on and get your health back. Works better, when you are in enemy creep wave. Plus AP and armor.

Abyssal Mask? Magic resist, magic penetration, ability power. I added this item instead of Archangel's Staff, because Archangel's Staff has only AP useful, and mana is already provided by Rod of Ages. Still not persuaded enough?
CAUTION MATH INCOMING
If you build Archangel's Staff, you have ~ 3300 mana at level 18 with your full build. Archangel's Staff himself gives you 45 AP and 1400 mana, plus his passive 3300*0,03~99 AP. Totally 144 AP and a lot of mana. Now look at Abyssal Mask. 70 AP and 57 magic resist, plus magic penetration aura. You lose 74 AP to raise your magic resist from 30 to 87. I'll count for you damage reduction percent.
Without Abyssal Mask (1 - (100/(100+30)))*100% = 23%
With Abyssal Mask (1 - (100/(100+87)))*100% = 46%
Now, what is 74 AP for Karthus? With his modificators:
Lay Waste 0.6*AP = 44.4
Defile 0.25*AP = 18.5
Requiem 0.6*AP = 44.4
Counting your cooldown reduction = 0 we can see your damage per second to single target, if you don't miss your Lay Waste and in range of Defile. 44.4 + 18.5 = 62.9
Now i will compare the damage you deal and damage you take. Let's imagine you are facing only one mage - Veigar. His combo at 400 AP (let's imagine he was not doing good, and have only 400 AP:) ) deals (30+3.5*AP/100)% of your current health +320+AP+260+0,6*AP+500+1,2*AP = 30%+14%+1080+2,8*AP = 44%+2200
If you have magic resist 30 (basic), this combo will deal 34%+1694 damage. Your health is 2370, after Deathfire Grasp 1564, which is < 1694. So this combo will shut you down.
if you have magic resist 87, this combo will deal 24%+1188. After Deathfire Grasp you have 1801 health, which is > 1188. You will have time to activate Zhonya's Hourglass, and regain health, and at the same time Veigar waits 16 seconds for his stun. With 87 magic resist you resisted (1694-1564)+(1801-1188)=743 magic damage more than with 30. With 62,9 additional damage per second, you will have to stay in teamfight for 11,8 seconds to deal 743 damage to single target. I have seen a lot of teamfights, only in few you will survive for 11,8 seconds without Zhonya's Hourglass and some magic resist, plus this damage is not resisted in this calculations.
That's why I claim that Abyssal Mask is better choise than Archangel's Staff.

There is a possibility of clearing up one space. Ask your team, if someone is going to buy Will of the Ancients. In case they do, you can choose one of "not ******ed items" below. I recommend to fill it with Archangel's Staff.

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SPACESPACE

Pros

SPACESPACESPACESPACESPACESPACESPACESPACE

Cons

Very good survivability. Very good AP. Zhonya neat trick. Spellvamp and magic penetration auras.

In early game you don't have the right to miss your Lay Waste. Just not with your mana.

REMEMBER! Build orders are fluid. You can switch some items with others to fit the situation.

I don't know what items you may want to sacrifice from my build, but here is a list of other choices.

Archangel's Staff Rylai's Crystal Scepter Doran's Ring Haunting Guise Void Staff Banshee's Veil Mejai's Soulstealer Deathfire Grasp Frozen Heart Morello's Evil Tome Warmog's Armor

Tell me about other items to test, if you want to see them here.

Void Staff discussion.
CAUTION MATH INCOMING
I am going to tell you why i don't like this item. I will compare it to Abyssal Mask.
They both give you 70 AP. The main difference is that Abyssal Mask gives you magic resist and 20 magic penetration, while Void Staff provides no survivability and gives you 40% magic penetration. 40% seems a lot, right? Well, it's not. Let's see on one champion, how much magic resist required so Void Staff will penetrate more than Abyssal Mask. If they are only items, that give you magic penetration (no runes), this number will be 50 magic resist. 40% of 50 MR is 20. So this item can be actually good, if you have no other magic penetration sources. But! The problem of this item is that it counts AFTER any other penetration. Let's see same calculation if you have Greater Mark of Magic Penetration and Sorcerer's Shoes. They penetrate 0,95*9+20=28,55. So when Void Staff takes effect? 50+28,55=78,55 magic resist. And that's true - (78,55-28,55)*40/100=20, same amount Abyssal Mask penetrates.
SO: unless enemy team all has 80+ magic resist, Abyssal Mask is better for damage, and it provides survivability.

You buy starting items, go mid.
First creep wave has come. Dont die. Don't push. You must lasthit every creep. That's how. If you are skilled enough, use my lane control section. Harras your opponent with Lay Waste.
Make sure you know your safety zones. (If you are blue on this pic!!!)
Credit to JhoiJhoi's Malevolent Morgana for the picture.
At first go back (level 5-7) you buy at least Catalyst the protector and Boots, teleport back. If someone on your team is going to buy Will of the Ancients, you start off with Tear of the Goddess instead of Catalyst the protector. Now you push your lane that's how, then clear your wraith and wolf camps that's how, push again, wraiths and wolves, and ect. You will outfarm your opponents this way.
In some cases you should skip camping and go gank instead, if you are 100% sure to get a kill (at least for a team) and no one of your buddies die because of that. Here is ganking section.
Don't forget to keep an eye on a map. You should always know what health do your enemies have, for obvious reason.
Until 17 minute you must have Sorcerer's Shoes and Rod of Ages.
Remember! When there is no teamfight coming, you must farm, gank from time to time, and stay alive.


If you are new with this game:
1. Activate Defile.
2. Find closest enemy, that does something in a fight. If there are no enemies left, go to 5.
3. Drop Wall of Pain on him. (if not on cooldown)
4. Drop Lay Waste on him. Try at the same time come closer, so the enemy will take damage from Defile. Go to 2.
5. Deactivate Defile. If some enemies escaped on low health use Requiem. Don't forget about those, who can survive Requiem.Warning 1. If you are going low on health, use Zhonya's Hourglass, when maximum of your opponents are nearby. Creep wave is also good. This will recover you.
Warning 2. If you were unlucky to die, use Lay Waste and Wall of Pain for 4 seconds, then decide if you can use Requiem, following this rules.
If you are good enough to think out your every step, you should decide your actions on your own. Try to kill squishy enemies first.

• Spellblockers: Sivir, Nocturne.
  Banshee's Veil.
  
  
• Shielders: Blitzcrank, Janna!, Jarvan IV, Karma!, Lee Sin!, Leona, Lulu!, Lux!, Malphite, Mordekaiser, Morgana!, Nautilus, Orianna!, Riven, Rumble, Shen!(Global), Sion, Skarner, Udyr, Urgot, Viktor.
  Hexdrinker, Maw of Malmortius.
  By ! i point out those, who can shield others.
  
  
• Healers: Alistar!, Cho'Gath?, Dr. Mundo, Fiddlesticks?, Gangplank, Karma?, Lee Sin?, Morgana?, Nasus?, Nidalee!, Olaf?, Renekton?, Sona!, Soraka!, Swain?, Taric!, Tryndamere?, Vladimir?, Warwick?, Xin Zhao?,
  All lifesteal and spellvamp items.
  By ! i point out those, who can heal others.
  By ? i point out those, who have situational heal.
  
  
• Those who have magic resist skill: Alistar, Annie, Galio!, Garen, Graves?, Jax, Maokai!, Mordekaiser!, Olaf, Rammus.
  By ! i point out those, who can shiels others.
  By ? i point out those, who have situational shield.
  
  
• Dodgers: Fiora?, Master Yi?, Vladimir, Wukong.
  
  
• Undyers: Kayle!, Tryndamere, Zilean!.
  By ! i point out those, who can make others immortal.
  
  I NEED YOUR HELP TO IMPROVE THIS SECTION! Not all the champions are listed here, because i didn't play them all.
  
  Tip 3
  How to lasthit creeps with Lay Waste
  
  When not pushing:
  Use Lay Waste only to finish creep, never for damage. Position your Lay Waste the way that it damages only targeted creep.
  Like that:
  When pushing:
  Kill ranged creeps, then melee with Lay Waste, and Defile, if you have enough mana.
  Try to position Lay Waste so it hits all three creeps.
  
  
  Tip 4
  Hiding your Lay Waste
  
  Some champions are dressed like ladies or priests, having skirt hiding their legs. Examples: Karthus, Morgana... Position Lay Waste behind a skirt so they won't notice your bomb before it's too late.
  Pictures coming soon.
  
  
  Tip 5
  How to clear creep camps
  
  Wraiths:
  Play Video
  Wolves:
  Play Video
  Q: Why placing here video of such an easy task?
  A: Because, I repeat, this game is mostly about farm. Outfarming your opponents is a key to success. Both wolves and wraiths give you 43+4*3+53+6*2=120 gold. They respawn every minute. So every minute you can have 120g more than your mid opponent. Of course, this is possible only in case if you have no jungler. But even if you do you still can clear camps from time to time.
  
  
  Tip 6
  Pictures of zhonya positioning
  
  Pictures coming soon.
  
  
  Tip 7
  Remember
  
  Every time you come back to base, you should buy on free money 1-2 Health Potion (until around level 10), and 1-2 Sight ward if you have a slot.
  Here you go, warding map for mid Karthus. Red is to prevent ganks. Yellow is for dragon, green is for baron. Other spots are not your task.
  
  
  Tip 8
  Requiem etiquette
  
  Alive Karthus:
  If you are sure you can kill someone with Requiem, and you have time to cast it, then do it. (Don't steal a kill though)
  If you have no time for that (you are fighting some champion(s) right now), you will need to finish your business before casting Requiem.
  While you cast Requiem alive, remember that you can be stunned or killed. This way Requiem goes on cooldown, dealing no damage.
  Requiem can be used to cripple enemy team before teamfight.
  
  Zombie Karthus:
  If you are sure you can kill someone with Requiem, and you have time to cast it, then do it.(Don't steal a kill though)
  If Requiem will be not on cooldown when you are alive again, cast it for damage.
  
  
  Tip 9
  Have more map awareness

  How? Simple. Ask your teammates to give you signal if they need you to dot the i's and cross the t's.

  
  
  Tip 10
  One more thing I want to point out.
  
  Don't steal everything. Your team also needs farm. And in late game you will have to stop at 6 items, at the same time your team will have like 3 or 4 items each. They will suck. You will suck because they suck, because you stolen their farm. Sucking sucks, right?

1. Choose the lane you want to gank. Your choise should be lane, where enemies will be at red or orange (If you are purple on this pic!!!), at the moment of your arrival. To make this happen ask your teammates to let the enemies push the lane, because you want to gank.Credit to JhoiJhoi's Nihilistic Nasus for the picture.
2. Push your lane. You don't want to have your tower damaged while you are away.
3. Tell your teammates that you are coming.
4. Choose target champion.

• Teleporters: Ezreal, Kassadin*, Katarina?, LeBlanc, Pantheon*(long cast time), Shaco, Twisted Fate*(long cast time).
  By * I point out those, who can teleport only at level 6.
  By ? I point out those, who have situational teleport.
  
  
• Dashers (Differs from teleport. Passing Wall of Pain still slows them): Ahri*, Akali?*, Caitlyn, Corki, Fiora?, Fizz, Gragas, Graves, Irelia?, Jarvan IV, Jax?, Lee Sin?, Malphite*, Nidalee*, Renekton, Riven(Very low travel distance), Sejuani, Shen, Shyvana*, Tristana, Tryndamere, Vayne.
  By * I point out those, who can dash only at level 6.
  By ? I point out those, who have situational dash.
  
  
• Speed increasers: Blitzcrank, Dr. Mundo*, Evelynn*, Fiora, Galio!, Garen, Hecarim, Kennen, Lulu!, Master Yi*, Rammus, Rumble, Singed*, Sivir*, Skarner, Udyr, Volibear, Zilean!.
  By ! I point out those, who can speed up others.
  By * I point out those, who can speed up only at level 6.
  
  
• Undyers: Kayle!, Tryndamere, Zilean!.
  By ! i point out those, who can make others immortal.
  
  
• Invisibility: Akali, Evelynn, Shaco, Talon*, Twitch, Wukong.
  By * i point out those, who can get stealthed at level 6.
  
  
• Special mentions:
  Gangplank. He can remove all crowd control spells on him, just by eating some oranges.
  Flash
  Teleport Enemy champion can use it to teleport back to base. You can deny Teleport only by stunning him. Also, anyone who have this spell can Teleport to the lane you gank.
  Ghost
  Do not towerdive stunners.

5. Correctly enter the lane you want to gank. You have to engage enemies from behind.
6. Put your wall on the targeted enemy.
7. Kill him.
8. Kill other enemy, if he is still here.
9. Get back to mid.

Each skill have its casting time. Lay Waste is, say, 0,1. (To be honest, I am not sure)
Every human being have reaction time, due to limited speed of light, signal from eyes to brain and from there to fingers goes in around 0,1 - 0,2 seconds.
That's why when you use Lay Waste, enemy does something in total 0,1-0,2 sec after he sees that red bomb. So you should aim your bomb into spot, where enemy will be in around 0,2-0,3 seconds.

Wall of Pain is easier to land, but still 0,1 casting time can make you miss. Keep that in mind.

There is no 100% sure to land a successful Lay Waste, right?
WRONG
Any champion, who is facing Karthus tries to stay out of his range, move unpredictably, and sometimes have speed increased (usually by starting with boot). But they always have a brief moment when they stand on one place. This happens when they lasthit a creep.
How to use this?
While doing your lasthits, you must watch your own creeps health. When one of them is going to be low enough to finish him, get ready. You should walk into an ideal position. It is when enemy is almost in range of Lay Waste, and he can't harm you. The creep he wants to finish should be between you, or at least somewhere nearby. When creep is ready to be finished, you drop Lay Waste on the enemy, making him to choose between taking damage and lasthitting, or dodging Lay Waste and forgetting about lasthit. If you are skilled enough and you know how to land a perfect Lay Waste, you can land an undodgeable Lay Waste(but only on enemy with basic speed).

Video coming soon.

Okay, i'll tell you the truth. This trick can be performed by ANY champion, if he is able to deal some damage to the enemy during enemy autoattack animation time.
But! Karthus is so awesome, that he can counter this by lasthitting with Lay Waste, thanks to low cooldown and manacost.

Go mid, get lvl 6, go to jungle. Now your job is only to killsteal. Your score should be (something) 0 (something less). Always remember to blame your team. Your items:

They give you CDR to use ultimate more often, and ridiculous amount of AP.


Sometimes decent players get trolled by dumb ******s, because they can't defend themselves. There will ALWAYS be ******s in public games, you have trash talk their *** back. Wipe that grin off their stupid face and show how dangerous reality/internet can be.

Why no gang?
Welcome to die.
(insert random player who was in the team battle) Why no stun?
Type "GG (insert random hero name who wasn't even in the teamfight) too fed"
HOUSE ON FIRE SORRY (leave game AND I AM NOT ENCOURAGING LEAVERS BUT GIVING YOU A LEGIT EXCUSE)
"Life of (insert ****ty carry name in here), farm for 40 mins, get owned, life is beautiful, too bad you spend most of it waiting for your hero to respond"
"Step 1 before you type anything think, Step 2 don't say it cause your gonna make yourself look like a ******"
Stfu and play (best opportunity is when someone types "b, ****, omg, I have boot, GG," etc you get the idea)
War does not determine who is right, only who is left
Even god couldn't carry you
If you were baron, you'd still be too ***** to go in
You know I actually think your dark and handsome. When it's dark, your handsome.
My play is better than your face
You have one brain cell, too bad it's fighting for dominance.
Don't feel bad, a lot of people have no talent.
It's not backdooring if the tower hits you first. It's called self defense.
Don't leave the base
If Karthus is a noob champion, why don't you play him?
It isn't where you come from, it's where you're going that counts
WOW i thought that was an illusion, either way you both die just as fast
I think you've got me confused with someone who gives a ****
I could eat alphabet soup and **** out a better (anything that requires words)
Can I borrow your face for an hour, since my *** is on vacation?
How much you pay me for that?

Note:
Practice is the next step into perfection. You cannot expect to read guide and suddenly become a better player. In reality you must adapt to your surroundings and predict. Knowing is half the game, but not all of it. This is one of the aspects no guide can teach you, no matter how informative it is. A prior example would be Ashe's arrow. You can read about all day and understand it's mechanism, but you will fail to land a perfect shot without pratice. Realisticly everything in life will play out differently then anticipated. Everytime you engage a team battle it's different, because their are too many uncontrolled variables like different timing, positioning, skills, etc. The dictionary is the only place that success comes before work.

Mistakes are a sign of progress. Experience is the name everyone gives to their mistakes.

To the new players, who just started playing. Don't play with AI all the time. Play in pubs. Getting owned and feeding is part of the game. Getting yelled at by an overly confident jerk is normal. The true "pros" are the ones that never give up. You'll only be as good as the people you are around.

Thanks to this obsidian destroyer guide, and CAPS LOCK LEORIC guide. They inspired me to write a guide.

Special thanks to jhoijhoi and his Making A Guide guide, and to CasterMaster, who reviewed my guide several times.


I followed your guide and I didn't win!
Blame your team.