Hi Mobafire people!
I've been playing Karthus for some time now, and I feel that I wanted to make a build for him. Many find Karthus to be a noob champion, because of his ulti, but I find him funny to play - He is a great farmer and good at harrasing. I don't know if a guide is needed, but I felt like making one. I hope you'll enjoy the build.

This guide is updated for the Nautilus patch, February 2012

Change:
- 20/8/11 - Added Void Staff to the core build and changed the item sequence to get Archangel's Staff later.
- 27/10/11 - Added further details in general.
- 27/10/11 - Changed the name of the guide

Pros
- Great farmer.
- Good harrasser.
- Awesome passive, which will grant you kills after you are dead.
- He can win teamfights, because he can do massive damage, even when dead.
- His ulti makes him easy to get kills with.
- When he has his wall ready he can be hard to gank. Especially with Flash

Cons
- Very squishee and bad survivability, when wall is on cd.
- He needs to be fed, to be good in late-game.
- He is often focused in teamfights, which means you'll have a harder time finishing them off, after you're death.
- Item dependant - If he lacks items, he will not do that big a difference in teamfights.

Skill Order

-> -> ->

Skills

Upon dying, Karthus enters a spirit form allowing him to continue casting spells while dead for 7 seconds.

- This is a ******* awesome passive. On of the best in the game, if you are placed right, when you die. When you have tons of ability power, you can do massive damage, even when you've been killed. When you get killed in a teamfight, spam Lay Waste or try and finish off your enemies with Requiem - But do not waste it when you are ganked or something, just because you panic. Requiem can also help your team to kill the rest of the enemy team, so you can use it to get assists, though it's funnier to get kills.


Creates a delayed blast at Karthus' cursor position. After 0.5 seconds, deals 40 / 60 / 80 / 100 / 120 (+30% of ability power) magic damage to each nearby enemy, this deals double damage if it hits only a single unit.

Cooldown 1 seconds | Cost 20 / 28 / 36 / 44 / 52 mana | Range 875

- For Karthus, this is what bewbs (BEEEEEEEWBZ <3) are to dudes - Sweet Beans! This is your main farming ability, until you have enough mana to keep up Defile, when your taking down another wave of minions. You will want to max this first, as it is your best harrasing skill and it gives you many minion kills. And minion kills restores a bit of your mana. It will benefit you most to use it on the ranged minions, as they are easier to kill. In early game mostly use it to farm, as it is quite easy to avoid, if you aren't pro at using it, since many start with Boots when they face Karthus in mid - When you are dead, try to take as much HP as possible with this. It can grant you assists or even some kills during a game.


Creates a 800 / 900 / 1000 / 1100 / 1200 distance wide wall through target point. Reduces enemy armor and magic resistance by 15 / 20 / 25 / 30 / 35 and reduces movement speed by up to 40 / 50 / 60 / 70 / 80%; debuff lasts 5 seconds. The wall lasts 7 seconds.

Cooldown 22 seconds | Cost 100 mana | Range 1000

- This is a funny and very usable skill. It is not even that hard to place, because of it's enormous range. You only want to choose this once in early game, as you won't need it that much, because you mainly meet ranged champions in mid - and Karthus wants mid. Why? Because C-****ing-Thulhu says so. However, it can be good, because it will slow down your opponent, if he/she tries to get close to you, to get a kill. It will also help you against ganking junglers - Wall of Pain + Flash = Easy escape (If performed proberly).
- In late game you can use this in teamfights to **** **** up. You can slow 2-3-4 opponents and go ape**** on their ***es with Lay Waste + Defile. Just make sure that you're ready to flash out of the heat, when they are getting too close to you.
- You can also use this skill to save allied champions. If they are getting chased, you can place this wall between the enemies and your allied. Sometimes the slow + your harrassing, is enough to get them of your allied's back. Note that the skill reduces armor and magic resistance quite significantly, so if you land this on the enemy carries, they will wipe rather fast in a teamfight. It also gives you nearly true damage in early game, since the enemy AP carry in mid, won't have much magic resistance.


Toggle Off: When Karthus kills a unit, he restores 20 / 27 / 34 / 41 / 48 mana.

Toggle On: Drains 30 / 42 / 54 / 66 / 78 Mana to deal 30 / 50 / 70 / 90 / 110 (+25% of ability power) damage to nearby enemies each second.

- This skill will be a killer machine in late game, when you have 800-1000 ability power. It can also kills a wave of minions in the matter of seconds. Early game, you can't use it that much, due to your mana pool, which will be drained quite fast. When/if you die, you pop this until, you're actually dead. It does massive damage each second, which can get you some kills, when you also use Requiem. There's not much to say about it except to use it for farming and in teamfights - When you have Zhonya's Hourglass you can flash in, and use Defile + Zhonya's active. This will do nice damage for some seconds, before you will get targeted.
- Sometimes you simply have to die, in order to win a teamfight, because you do most damage in the middle of a fight. Don't be angry, if you don't feel you have been protected well enough, because the AD carry is more important in the end. The carry mush finish them of, if you can't. The AD carry has better pushing-potential after a teamfight, since he/she wrecks towers faster.


After channeling for 3 seconds, Karthus deals 250 / 400 / 550 (+60% of ability power) magic damage to all enemy champions (regardless of distance).

Cooldown 180 / 150 / 120 seconds | Cost 200 / 300 / 400 mana | Range 10000

Cooldown 0.5 seconds | Range 550

- If Lay Waste was bewbz to boys, this must be what Robin is to Batman. (I don't know if that's better than bewbz, but I did not know what else to say.)
This spell will grant you a lot of kills if you use it well. It is mainly made to finish of enemies with low hp. Make sure that your teammates tell you, when to finish someone off. And they better tell it fast, because it pisses Karthus of, when his ulti is wasted and he can't finish the next enemy off. It really sucks if they have Banshee's ready or Zhonya's active. Then they will ignore the spell, so try to see if their Banshee-shield is up, before you finish them off. When you have used this spell, try and get the blue buff for cooldown reduction. Just make sure that you get some kills with this, because you need to get fed, to get items. If you are under-fed, you'll have a hard time, believe me.

Preferred summoner spells

+

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- This is really good for Karthus. You can escape with it, sacrifice yourself to win a teamfight with it. When you escape just flash and use your wall and run safely away. I go with this most of the times. However, it is not a must have.


- I also prefer this over other summoner spells. It gives good map control and you can get back to your lane fast, after you've shopped. You can also enter fights and change the outcome of them. It it also nice for protecting towers, which are under attack. Some use Teleport + Revive on Karthus - But that requires quite some skill to master, so feel free to do it, when you are a more advanced Karthus.


- This is also a great summoner spell for Karthus, since he is kinda slow. It will benefit you in teamfights, when Defile is on. You can catch up with the other team, when you are harrasing them. As always, it can also be used as an escape spell.


- This spell is great to finish them off, but you already have your ulti to do that, so I like other spells better. However, it can be used to get them down to the amount, where your ulti can take them out.


- I've seen some Karthus use this summoner spell and I've wondered why. Sure, it does help you keep up your mana pool in early- and midgame, but in lategame it is almost useless. You don't need that much mana to farm and harras in my opinion. I think other summoner spells benefits Karthus way more. He needs escaping options and map control is also great, so I wouldn't recommend this, unless you really have a hard time with mana issues.


- This is a great spell for first blood and to stay in lane, but since you run solo (with Karthus) you won't be able to get first blood that fast (Unless your enemy is kinda bad). I prefer Teleport, which means you can recall, get hp and mana and get back to your lane fast. This is not a spell, I would go with, but if you feel like wanting that extra survivability, just go with it.


- Combined with Teleport it can be good. Otherwise, don't pick it.

I haven't tried other spells, but Exhaust might work, but it would be a very defensive spell, 'cause you already have your wall to slow, when you attack. Cleanse can also work, but you are so squishy, that you might get killed, even though you use it to get out of CC.

Offense
I take 9 in offense to get:
- Extra AP
- Extra magic penetration
- Cooldown reduction

Utility
I go with 21 in utility to get:
- More Mobility
- Some spellvamp for more sustain.
- Extra xp
- Lower cooldowns on my summoner spells
- Lower cooldowns on my abilities.

You can go with other mastery trees, if you prefer. This is simply my way, which fits me the best. I think mastery trees are quite individual - You could go defensive for better survivability.

Marks
9x
- These are simply to make your spells do more damage. Spell penetration is a typical choice in marks, when you play a caster. They benefit your Lay Waste nicely in early game. Combined with Sorcerer's Shoesand masteries, you're close to dealing true damage in early game.

Seals
9x Greater Seal of vitality
- Gives you a decent amount of HP, which will greatly help you, since it scales throughout the entire game. In level 18 these runes give 175 HP, which is great, almost as much as a Ruby Crystal provides.

Glyphs
9x or 9x
- These will give you some extra damage early game, which will grant you more minion kills and a better harrassing capability. You can also go with AP/per lvl runes, if you prefer that. Those will not give that much damage early game, but they will give you a bit more mid- and late game. Alternately you can use AP/Lvl glyphs, since they scale better into lategame.

Quintessences
3x
Just to give you a bigger damage output early game. Same reasons as with the glyphs. You can also exchange this for a AP/per lvl rune, but I would recommend these, it will help you zone your opponent in early game.

- This is the build I often find myself using. It gives great damage and decent survivability. There are, of course, other ways to build Karthus, and I will list alternate builds as well.

Things to consider

- This is so close to going into my core build. Only thing is, that you'd have to replace it with something. You can't miss out on the mana regeneration from Archangel's Staff, neither the AP from Rabadon's Deathcap. The active from Zhonya's Hourglass is also kind of a must have, and so is the magic resistance from either Banshee's Veil or Abyssal Mask. So you need to skip the magic penetration from Void Staff to get the spellvamp and 80 AP from Will of the Ancients

VS
- I think these two items are almost equally good on Karthus. If you prefer rushing Catalyst the protector over Tear of the Goddess and grab Rod of Ages, then feel free to do so.

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Early Game

- Start with this item, in order to keep up your mount of mana. You will want to be able to use Lay Waste a lot in the beginning, in order to farm and harras. You can also build in to Archangel's Staff later on, after you've grabbed your boots. You can also start with Meki Pendant] if you prefer regeneration over a bigger pool. The reason why I prefer a bigger mana pool is that, if you're able to zone your enemy and get them low on HP, then you have a huge advantage in laning phase, since the enemy will have to stay back, so they wont be ganked by your jungler. If you have [[Meki Pendant you might run out of mana quicker, and then wait for your pool to regenerate. It's mainly just a matter of what you prefer. ^^


- Grab two of these or one of these and a mana potion, before you go to your lane. They will make you able to stay in lane, for a longer period of time. You don't have to worry that much about losing 30-40% hp in the beginning, if you have 2 of these badboys. Just consume one when needed and keep farming! If you're confident that you won't lose that much HP you can go with 1x HP Pot and 1x Mana Pot.


- Karthus strongly benefits from mobility,


- Simply for a bigger mana pool, to spam your Q as much as possible. Also helps keeping up your E-ability and it should assure that you have mana available when you need to kill someone with your ultimate.


- Grab these, the first time you recall. This does not necessarily has to be that late, because of your teleport. If you have more money, you start building further on the Arhcangel's Staff and you can also buy a hp pot.
- These are the best boots for Karthus in most games. They will penetrate some of the opponents magic resistance. In some games other boots are needed, but more about that later.

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Mid Game

- When you get this, your ability power will rise like an erected *****.(Do not feel disgusted, I'm European) It will give you 155 AP + 30%. Your ability power will now do tons of damage more or less. You simply want this item to boost your damage, so your ulti can finish them off even earlier. Your Defile will now be able to rape minion wave after minion wave.

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Late Game

Build Archangel staff for the mana and the AP. You can also rush Rabadon's and wait with the staff. As long as you don't run oom. If you start with AA you can start building Rabadon's Deathcap in midgame, if you have the ressources for it.


- This item will help you a lot in teamfights. When you are focused, you need to use it's active. It requires some timing in order to survive. If your team is struggling, flash in with Defile activated. Then spam Lay Waste and when you are getting attacked use Zhonya's active. Then they start attacking someone else, while they are damaged by your defile. You might get killed, but the most of the other team will as well.
Note: Throw your wall on the opponents before you jump in. This will grant you some extra survivability. So will this item with a bit of armor. And the 100 AP is also kinda sweet beans - I haven't done any math, but you'll have a lot of ability power. Your damage output will be sick now.


- Simply for more survivability against the opponent caster, since he/she probably will try to **** you up. The aura also benefits you alot when having Defile active and you're popping Lay Waste like a baws. If you feel the need for more effective HP, then grab Banshee's Veil instead. You will miss out on some damage, but


- This badboy will boost your damage output alot and melt through that MR, which the enemies buy to counter your ultimate. Try to keep track of when enemies have the shield up on Banshee's Veil, so you don't waste your ultimate. This is simply a great lategame item.

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Survivability oriented build

- This build provides alot of HP and some nice armor & magic resistance, while you're still able to dish out alot of damage. A good build against casters, who can really lock you down.
- Malzahar, Veigar, Kassadin, Annie.
If you want to use this build, I recommend just going with 3x Greater Quintessence of Scaling Ability Power.

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Cooldown Build

- Grab Morello's Evil Tome after boots, and then skip Void Staff in the end of the build. This will make you hit the 40% cap with blue buff and masteries.

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Optional Items

Rylai's Crystal Scepter - HP, AP, Slow - Great for a mix of HP damage and utility.

Will of the Ancients - This is so close to being in my core build, perhaps instead of Void Staff. It is so cheap and it gives great stats. Perhaps get it after Sorcerer's Shoes if you want to grab it.

Moonflair Spellblade - Kind of lackluster, but if you really need the CC-reduction, you might grab it. But it scales really bad into lategame, so...

Frozen Heart - A great armor item, which provides CDR, as well as mana and a nice passive. Grab this if you want CDR, survivability and a bigger mana pool.

Guardian Angel - Gives a nice mix of armor and magic resistance. Only get this, if you feel the revive will benefit you in teamfights. Often it is just a waste, so it is a bit risky to get.

Banshee's Veil - A great item to replace Abyssal Mask. Good against hard CC abilities. Gives more mana for more damage (AA Staff).

Lich Bane - Not that great on Karthus, but if you really need to push, then you might get this. With Defile, he is actually a pretty decent pusher, especially with Lich Bane.

Quicksilver Sash - Facing Warwick, Malzahar, Urgot or someone else, who can **** you up? -> Grab this instead of Abyssal Mask. That way you can cleanse out of their suppression or another hard CC.

Mejai's Soulstealer - I'm not a fan of snowball items, but if you really dominate and you can feel that the enemy team is bad, then you can grab this. Just never get it against capable opponents.

Morello's Evil Tome - The CDR will make you reach the cap with blue buff and masteries. That way you can use your ultimate more often to secure more kills. It doesn't provide as much AP as some other items and the mana regeneration isn't really needed, so I don't get it that often.

Rod of Ages - Either grab this or Archangel's Staff. If you face strong harrasers like Malzahar, Kassadin or LeBlanc then rushing Catalyst the protector is a good idea.

Remember than you can't use the same build in each match. Items are situational!

- Ashe is not that big a problem to lane against. Everytime she tries to get close to you, throw a wall at her and spam bubbles at her. You will also be able to farm better in most matches, because you have Lay Waste & Defile. Just care when she turns level 6 and had stun. Try and get someone to gank her, so she can be denied as much as possible. This will give her a hard time as a carry.


- Anivia can really be a pain in the *** for Karthus. Anivia has more damage than Karthus early game and more survivability when her egg is up. Play safe and farm well, but I wouldn't recommend that you try to kill her 1v1. If you have a jungler, get him/her to gank Anivia. See if you can get the kill in order to be fed, so you have an advantage against your laning opponent.


- She is really annoying, because it's hard to plave a wall on her, due to her blinks. She can get close to you, do damage and get back, and you won't be able to do as much damage on her, as she does on you. However, keep yourself behind creeps and farm with Lay Waste.


- Mirror-lane is fine, especially if you have better jungler than the enemies. Get the jungler to gank as early in the game as possible, so you have an advantage. It's really about who is best to last hit creeps and harras the other, if it is Karthus vs Karthus -> Hopefully it's you.


- Against Teemo you should do fine, because his blind, won't affect you that badly. Just throw a wall at him and spam your spells at the little dude. This should keep him off your back. When he has mushrooms you might want to get an oracle, so you can destroy his shrooms. It will make it a lot easier to gank him and piss him off.


- You do not want to face Le Blanc. Her damage is massive early game, and you will have a really hard time hitting her with Lay Waste, due to her blink. If she plays well, you will probably be denied a lot and have a hard time in mid/late game. Just play really safe and try to farm as good as you can. Get your jungler to gank as often as possible. She scales badly into lategame, so if you haven't fed her, you have the advantage.


- She can be pretty annoying, but you can stay behind your own creeps and farm. Just make sure, she doesn't hit you with her stun. Try to harras her and see if you can get a kill at lvl 6. It's really just about avoiding her skill shot and to farm better than her. Try to make her run around a lot, by spamming bubbles at her.


- I find Kennen to be really ****ing annoying to lane against. However, it is possible, just play careful and try not get hit by shurikens. When you & Kennen hit level 6, have flash ready, when Kennen might use ulti on you. Also try to outfarm the ninja, so you have an advantage in your items.


- Watch the **** out when you see this little *****.. She is devastating when she hits level 6. Care and try to get your jungler to gank her to get an advantage over her. Just try to far, but stay safe. Keep track of her passive, so you know when to have flash ready to escape her stun.


- ^Same as Annie. However, you can make him less dangerous, if you stay behind creeps, so his stun isn't gonna hit you. However, his burst damage is way higher than yours, so try to get your jungler to gank or try to become fed from killing other enemies with your ultimate.


- He is a really strong pusher, so you might need ganks on him as well. When level 6 he can shut you down, so be very aware of your HP, so his combo won't necessarily take you out. Perhaps rush Catalyst The protector for more sustain, instead of Tear of the Goddess, cause he will harras you and keep farming. A tough champion to face, but simply try to farm and hope for an opening to kill him.


- She is a long range harrasser, but watch out for her autoattacks as well. Keep your distance and perhaps buy Boots fast to avoid her ball better. Keep your distance and farm the best you can. Orianna is really strong, so you might have a hard time.


- Deny him the best you can and watch the **** out when he has his Primordial Burst. If you can't manage to do that, you're probably ****ed xD
Try to get a jungler to gank him, so you can get a farm and XP advantage. Just constantly harras him with Lay Waste, so he has a harder time last hitting with his Q.

How You Start
Buy your starter items and go to your lane - mid. Either harras your enemy champion with bubbles or hug your tower and wait for minions. If you want to harras the enemy, care for ganks, because you will have to go far away from your tower to harras.
When minions arrive, your farming starts.

How You Farm
Last-hit with Lay Waste and autoattacks - Ranged minions are easier to kill in my opinion, since they are squisher than the melee creep. Timed right, this should give you at least 2/3 of the ranged minions. When the ranged minions are dead, try to last-hit the melee minions aswell. Later in the game, when your mana pool is bigger, you can use Defile to kill minion wave after minion wave, in a matter of seconds. You can also go to the creeps in the jungle and kill them with Lay Waste or Defile.

How You Brawl
Karthus does not use his fists (That's what she said). He uses spells. Harras your opponent with Lay Waste, if necessary. If not, simply outfarm them - Get more creep-fed than him/her. Don't get too close, since their damage output will be more than you can manage early game, since it requires your bubbles to hit simultaneously to really harm your opponent. If you get attacked, spawn your wall on the opponent and spam Lay Waste on his/her ***. This should get them off your back. When you are level 6, wait for enemies to be nearly dead, and finish them off with Requiem. Make sure that your teammates tell you when to use it. This should get you fed on kills,.

How Karthus gets really hated
If the enemy team has a jungler, try and ward the dragon. They will probably go low on HP, so when they are almost done, use your ulti. Afterwards be ready to steal the dragon, if they die. Just don't get ganked, so have flash ready before you do this. Try to make your support use Clairvoyance to keep track of the enemy jungle, so you can give him a harder time - This will support your team, since the jungler will have a harder time ganking.

Ganking in side-lanes
Karthus is really good at ganking in side lanes, since his wall will give a huge advantage, when you fight 3v2. The enemies can't defend themselves when they are slowed so bad. What you can do is to go to the bush, right before you enter a side-lane (You know which one) and wait for an opportunity, where they are in range of your wall. If you want to surprise them, go to the bush near their tower and flash up behind them and spawn your wall on them. Try to hit both, but one will also do the job. Just make sure that your teammates are ready to gank and don't leave you with 2 enemies. Especially if you just used your flash, so you have no escaping possibilities. This will piss you off and feed the other team. xD
-> Try to make the tankiest of you and your teammates tank the tower, if you need to towerdive when ganking. Teleport can also help you set up some nast ganks if you make your teammates put a ward in one of the lane-bushes.

Ganking mid
This time you'll need a jungler or a teammate from another lane. Do not gank if your opponent has flash ready, it will be a waste of time, unless your mate have stun and you can finish him/her off, before they can flash away. Use your wall on the opponent and get your teammate to help killing the enemy, while he/her is slowed. Simply spam bubbles on them, while your mate also damages the target. They should die, but if they don't just push the tower when they are recalling, because they need hp.

Karthus can be a tricky champion in teamfights. It can be hard to place yourself right, but try to wait for the tank or someone else to initiate and then spam Lay Waste and run near them with Defile. You will probably be a main target now, so if you have Zhonya's active, you use it when you feel like you need the 2 seconds protection. Have Defile active in these 2 seconds. It will do quite some damage and afterwards you can try and flash out of the heat. If your team is struggling with winning you can make a kamikaze attack, where you do as much damage as possible before you die, and then you go ape**** with Lay Waste or Requiem.

NOTE: Do only use Requiem, if it can grant your team kills. Do not waste it on nothing, like when players panic-use it when they die. -> Unless the respawn timer is so long, that it will be ready after you're alive again. Then you might as well use it for the damage output -

Try and slow the opponents before a fight. That way you might do some damage before the fight even starts. Karthus can change a teamfight, but if played wrong he can also be kinda useless in teamfights. After a teamfight you might be able to finish them off.

Note: Always try to hit the carries with Wall of Pain to reduce their armor and magic resistance. That way you and your team can kill them faster.

I will probably write more in this guide later, so if you have ideas for sections to add, please tell me. I hope it will help people, who are playing Karthus or people, who want to play him.

Thanks for reading!




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