Build Guide by Lvx

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League of Legends Build Guide Author Lvx

Karthus - MagPen, a royal pain in the *** (AP hybrid)

Lvx Last updated on July 29, 2010
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Ability Sequence

Ability Key Q
Ability Key W
Ability Key E
Ability Key R

Not Updated For Current Season

The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.


Brute Force
Improved Rally

Offense: 9

Strength of Spirit
Veteran's Scars

Defense: 0

Expanded Mind
Blink of an Eye
Mystical Vision
Presence of the Master

Utility: 21

You can find my other build and ideas as well as calculations about maxing out other champions potentials here:
Alistar (build)
The mathematically proof, that you can one-hit towers with Alistar, and have a great heal as well as an amazing dmg output against units at the same time.

Doc Mungo (build)
An idea, how to max out his HP and his harrassing potential. You will find quite detailed information about armor penetration and critical strikes here. Graphs included.

Kayle (build)
Dedicated information about game mechanics and showing the effects of pure AP / pure AD and hybrid builds on Kayle. Graps included.

Zilean (build)
Some calculations about cooldown reduction and AP. You will find information about magic resistance and magic penetration here. Graphs included.

Another Karthus build... why the heck?
Rather simple: I did not find the other ones sufficent, beside the fact that I respect your efforts taken, and want to express my gratitude to other guide authors - without some of the ideas of your guides, I would probably have dropped Karthus already again.

As this guide is going to be quite long, I marked the vital points orange, for those of you that are just looking for a first glimpse.

//Edit: For some reason the skill sequence is messed up, and I cant change it. You, for sure, dont skill one skill 6 times ;). It should rather look like this:

Maybe the DB will accept the changes later on... //

At first, I want to lose some words about Karthus pros and cons:
    - Incredible magic damage
    - Global nuking skill (R: Requiem)
    - Built-in evading skills
    - Great farmer
    - Built-in crowd control (CC and DD on one char!)
    - Independant to buffs

- Mana depandant like hell (no pun intended)
- Slow char
- Squishy in late game

Runes, Masteries, Summoner Spells
Let's go with the runes next.
I renamed this build to "AP-hybrid" for a reason: there is no AP runes. Let me stess out one point very clearly - AP runes are a waste of IP, of space in your runebook.
See this calculation sheet to see what I am talking about (further details down in the comments).
The amount of AP gained due to AP runes is first of all of no interest for our main ganking skills (Q: lay waste, and E: defile) as lay waste has a 1s CD and defile deals DoT. So that AP we abdicate here would only mean miliseconds in battle. Looking at our ulti, requiem, it means not enough damage to think about it - we'll have over 950dmg anyways. Enough for our needs.
Instead we go for:
which will provide us with 23,4 MP (magic penetration).
will moreover give us 24,3 MR (magic resist) at lvl 18 (at lvl 10 it already buys out the glyphs of warding, and we will reach lvl 10 fast) and 12,69 armor.
We take both of it gladly, as we wont spend any money on armor / MR items. On the other hand, according to our playstile, we welcome any protection we can get.

The benefits of these runes are greater, then the deprivations of letting other runes go.

Heading on to the masteries
We go for a plain and simple 9/0/21 mastery tree, in order to optimize our magic penetration and and utilities. Business as usual.
Slightly uncommon, you might recognize the "haste" mastery. According to our summoner skills, it fits in way better than "spatial accuracy" or "blink of an eye".

The choice of the summoner spells...
That is where the wheat is seperated from the chaff. There is a very basic rule and that tells us:
- NOT to pick clarity, as we have mana from "defile"
- NOT to pick exhaust, as we have "W: wall of pain"
- NOT to pick ignite, as we can finish of with "requiem"
beside that, we leave "cleanse" and "smite" to the tanks and junglers. If we would ever need "cleanse" to get away, we messed it up anyway.

What we are aiming for is: map control. You might of your choice use "flash" or "teleport" as well. The advantage of "ghost", anyway, is quite obvious:
1st you have a 40% speed boost for 15,5s. Way better for "defile-chasing" enemies then "flash". And: you can escape with it, the big advantage in comparsion to "teleport".

The skill we might feel like changing is heal. No deal about it, there is alternatives:
- clairvoyance, if your team has a good communication. I personally would not take it for a random game, as it like castin pearls before some swines in most cases.
- ralley, if you are playing with some brute tanks dealing normal damage.
But I prefer to pick heal to play it safe, when it comes to close combat with Karthus.

Our items - or "why is that guy so damn annoying?!"
As I told you above, we will not waste any runes to AP runes. The reason is quite simple:
With the
+ 3.400 mana * 0,03 = 120 AP from archangels
and the x1,25 due to zhonya's we will have 555 AP. That will be totally fine for us.

lay waste will do 282dmg/s / (564dmg/s if hitting a single champion)
defile will do 245dmg/s 0 MR. And with "wall of pain" will reduce our enemies MR by 35. Plus 75,91 magic penetration in total (sorceress shoes + haunting guise + runes, * 1,4 due to the void staff). So in most cases we will solidly deal our 800+dmg/s to a single champion we attack. Or ~530dmg/s if we decide to bomb several heroes at the same time with our "lay waste".

To be mentioned: by that time, our ulti will do 930dmg - that is 814dmg after enemies MR (which I supposed to be 70, for further details see the link above). So in case an enemy heroe should try to escape, or you should get killed, with some half dead DDs around you... be sure, you will get them down ;).

Anyways: This equip is quite expensive. A quite cheap way of acquiring AP is to buy "mejajs soulstealer". But only buy it, if your K:D is solidly positive. If you are going to die more often anyways, you might want to stick to the item purchase provided above.
About item variations
1.) While you would want to buy "catalyst the protector" asap, and while "abyssal" is the icing on the cake, you are pretty flexible about everything else.
I find it clever to get "rod of ages" quite early, as it will increase your AP over time. If you are going for "mejajs", this would be a good point to do so.

2.) If you have problems with your mana pool, you might want to go for "archangels staff" or at least its component "tear of the goddess" before "void staff". I for myself have made the experience, that after ganking (one to three heroes at a time, depending on your teams support) a trip to the base to refresh is a good idea. So I dont need mana that desperately but go for the MP first. Feel free to change that order.

3.) In some cases, if you really fail to keep your health bar up.. think about a "hextech revolver":

It costs almost nothing, and gives you 10% spellvamp (the reason laning against morgana sucks so hard..). Dealing 280dmg with one "lay waste", you can recover over 80HP/s by using it on creep waves. I do not really suggest to buy that item - but it would work.

The playstyle. The only style we have got, but plenty of it.
Okay, first of all, lets take a look on our skills again (I wont post their details here, but you will find them at the skill sequence box above, as a hover effect).
Your passive ability "death defied" allows you to cast spells for another 8s after you were killed. That is a pretty cool passive, since:
- you can still cast your ulti (see below) if you got good chances to kill,
- you can take some enemies with you, with 4-7 well placed "lay wastes" (depends on your reactions) and of upmost interest:
- you can still toggle on "defile". That is very useful, as it won't end after the 8s but stay on, until your mana is all gone. So you might want to hit "E", right after you were killed. Especially if a team fight is still going on, your mates will be grateful for the support you are still giving.
Oh and... the enemies will enrage, when they are killed by a dead buddy...

Next you will recognize, that we skill "wall of pain" at lvl3 already, oposite to most other builds I've read.

Let's focus on that skill for a second, as it is probalby the most awesome skill Karthus has.
    - It creates a wall, that lasts
7 seconds (in comparsion: the one of Anivia only lasts 5s, and has no effects at all)
- It greatly increases your chances to escape, by slowing enemies by 40%-80% for 5s
- It lowers their MR by 15-35 for 5s. That means: Creeps that have to move through our wall, will die way faster from "lay waste". It will make the ganking very comfortable, especially if you are not the only mage involved (Ryze and Annie, i.e., will love you for this!)

As we dont want to tower hug all the time, this gives us opportunity to escape after harrassing even DPS/tanks like Mordekaiser, or to slow down and finish of squishy opponents, like Annie, Ryze, Fiddle, Shaco, etc. If you get used to this skill, it will give you a huge amount of CC you should not miss.

"Lay waste" and "defile".
I wont lose many words on those skills, as they should be already known to the bone, or at least be very easy to experience. So only the most important aspects:
- "lay waste" deals double damage (later on above 580!) if you hit a single target. When harrassing enemie heroes, try to place it in the direction they are heading to, or next to them when they stand beside their creeps:
[C][H] [x], where [x] indicates the place you should place the skill, to make sure no creeps lower its dmg. As it has a 1s cooldown, spam it whenever possible. Nice to harrass enemies big time, after they pushed you back to your tower.

"Defile" is, right after "wall of pain" the second skill that is used way to rare: It deals a hell of dmg, and it has a quite nice range of 500 around Karthus. So if you chase enemies, or if you escape: throw it, if you can afford it by your mana. It prepares kills, or keeps chasers away. If they don't accept your privacy - force them to.

Beside that, it grants you (as long as it's off) 20-48 mana/kill. Use it to keep up your manapool: active, lower the creeps HP, deactivate and place a "lay waste". Gives you huge amounts of mana and even more important: gold!

Finally we get to your ulti, requiem.
It is a decent nuke, as it takes effect globally: After a 3s channeling time, all enemie heroes will be dealt dmg. Actually quite simple system.
What makes my eyes bleed is two horrible mistakes, that Karthus summoners repeat over and over again. Never, but really NEVER, do one of this:
1.) See requiem as your personal K:D-pushing nuke. You are playing in a team, so feel free to use your ulti to assist your teammates with their ganks.
1 kill for your mate and 1 assist for you is WAY better then waiting till your mate is down, and then finishing of the enemy with requiem. That grants your team less money (only for 1 kill instead of 1 kill and 1 assist), and even worse: it feeds the opposite team. So try to have an eye on the map, and feel free to use your ulti for defensive purposes as well.

2.) But even worse is blindness or ignorance:
You will at any time of the game know the exact amount of dmg that your ulti deals, +-10dmg MAX!
So when you see a possible target that's escaping your mates (try not to killsteal, they'll rip your balls of and wont support you anymore...): Click it, and check its health.
Do NOT use your ulti, if:
- The difference is less then 30HP (more, when it's Garen, Yi, etc.)
- Your target is standing next to Soraka, Tarik, Alistair or any other healer or an enemie that has his "heal" for sure off CD. As your channeling time is 3s, and your attemp will be shown by red lines over the enemies heads, they will most probably ruin your attemp. While your skill is on cooldown after that fail, you will at least see two other chances to kill, and bite yourselves' *** for not having your ulti ready ;).

Finally a word about ganking
If you face a Karthus that gets his most kills by his ulti, you can tell that he is a ******** bad Karthus.
Most kills you will make by your three normal skills. As "defile" is an aura, and "lay waste" has a cool down of 1s max (btw. that is why we did not buy a single CDR rune) you are always ready to gank, as long as your HP / mana are up.

Other then some heroes, you dont have a specific combo you would have to focus on (like W-E-Q with Pantheon or R-W-E-Q with Ryze), so you can lean back and focus on your health bar and on spamming "Q".
When enemies approach you, let them come close, activate "defile" and as soon as they stop moving, pull a "wall of pain" right through them. If they escape: chase them - if needed by "ghost", and put the wall into their direction. They will mostly cross it before they actually see its animation... and at that point they are doomed already.
In both cases business is:
1st get them within your "defile"
2nd make them cross a wall / plant it on them
3rd spam "lay waste" on them till their exitus. It mostly wont take very long till that point.

In case you face invisible enemies (and there is no eyes or oracles around): defile works on stealthed enemies as well. So if an almost dead Shaco jumps away, or an Akali hides in her shadows: You can wether stay around with "defile" on and hope to catch them (most of them get quite aggressive, when they are doomed anyway, and will come back to finish you off.. mostly they fail badly). The alternative is to get some meters away to a save place fast, and activate your ulti. As "recall" has a 5s channeling time, you will in most cases even get them before they have a chance to make it to their base.
(What is actually the most annoying point about Karthus: You can run, but if he is well played, you simply won't make it)

So, in short terms:
Use your wall of pain often.
Use your ulti rational.
Try to avoid solo actions, when enemies are missing.
Have fun ganking...

About the author
As you might see, this is my first build. Anyway, I am playing Karthus for a while now...
My summoner lvl is 22, so my rune page is not full of tier 3 runes yet, nor are my masteries (I am playing a 9/0/13 now for that reason).

Still by using this build, my K:D-ratio is in almost any game way positiv and before the matchmaking has been changed to lvl30 req. for ranked games, I proved some ppl quite wrong for their thesis, you'd have to lose with players below lvl30.
What I'm telling you by that is, that there might still be spots where this build could be improved, and I would gladly hear about your ideas to work it over. But nevertheless this build can be played without a single rune (tried it, succeded with it) as it mostly depends on items and players skill (seeing chances, find the time to back off).

I'd appreciate if you gave that build a try, and a rating +1 if you liked it. Thanks