Karthus Build Guide

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MirageTanks Guide to Why the Hell does Everyone Play Karthus Wrong?

written by MirageTank

Karthus Build

Table of Contents

  • Introduction

    I am writing this guide because KarthUs is my favorite caster and I want to teach the people the secrets behind this badass Lich and so everyone stops stacking Archangels on him. Yes I am frustrated.

  • Abilities

    Death Defied
    Upon dying, Karthus enters a spirit form allowing him to continue casting spells for 8 seconds. During this time his abilities cost no mana. His death timer is also reduced by 20% to compensate.

    Recently buffed, this ability is probably the most unique in the game, and one of the most underrated passives as well. Being a squishy caster is a tough life, and unlike Kassadin you can't flash over walls, cliffs, and fat men throwing barrels at you when the going gets tough. So you die. But when you die, you get to stick around and nuke the s$%t out of everything stupid enough to stand around your corpse. Lets you throw in your ult to get the kill on that guy who just barely escaped you. Or put up walls and lay waste for your team to win the teamfight after you're gone. This passive is the reason focusing Karthus first is always a wrong idea. The hardest part of playing Karthus is remembering that you have this and to spam spells while dead.

    Lay Waste
    (Active): Creates a delayed blast at Karthus' cursor position. After 0.5 seconds, deals magic damage to each nearby enemy, damage is doubled if it hits only a single unit.

    * Cooldown: 1 second
    * Range: 875

    Cost: 20 / 26 / 32 / 38 / 44 Mana

    Magic Damage: 40 / 60 / 80 / 100 / 120 (+0.35 per Ability Power)

    Your super rare awesome chocolaty fudge coated mega super nuke. Low cooldown, high damage AOE skillshot. If Karthus was a ranged DPS, this would be his autoattack. This is your main form of damage all game and lane control. It farms your creeps, harasses your enemy, and lategame does MICHEAL FUCKING BAY EXPLOSIONS worth of damage to single targets. If your target is alone it does double damage, meaning laning this on champs who stray too far from their minions will make you the god of the lane. It's the first spell that makes Karthus, Karthus.

    Wall of Pain
    (Active): Karthus creates a wall between 2 obelisks at target position. Any enemy passing this wall have their armor, magic resistance, and movement speed reduced for 5 seconds. The wall lasts 7 seconds.

    * Cost: 100 Mana
    * Cooldown: 18 seconds
    * Range: 1,000

    Wall Width: 800 / 900 / 1,000 / 1,100 / 1,200

    Armor & Magic Resist Reduction: 15 / 20 / 25 / 30 / 35

    Slow: 40 / 50 / 60 / 70 / 80 %

    This spell just rocks. It's a huge wall that is easy to land and makes Karthus do that sweet damage that he do. Landing this on top of an enemy in lane means they are in for the hurt of they don't dodge your Lay Wastes. Throwing this in a teamfight means the entire enemy team recieves a giant AOE armor and magic resist reduction, and are 80% slowed for 5 seconds. Enemy running? Throw a wall down to snag 'em. Getting chased? Wall, and lay down Wastes in front of them as they futility try to catch you. It's basically a YOU SHALL NOT PASS area, meaning they have to go ALL the way around the wall, go through it and die, or just turn around. It is really a dynamic spell that changes the face of the battlefield. It's the second spell that makes Karthus, Karthus.

    Note, it comes out perpendicularly to your body, meaning trying to catch someone from the side will be difficult. Landing the line directly on top of them still slows them, or you can try and angle it.


    (Toggle) - Off: Karthus steals energy from his victims, gaining mana on each kill.

    On: Defile drains Karthus' mana to deal damage to nearby enemies each second.

    * Cooldown: 0.5 second
    * Area of Effect: 450

    Mana Gained: 20 / 27 / 34 / 41 / 48

    Cost: 30 / 42 / 54 / 66 / 78 Mana per second

    Magic Damage: 30 / 50 / 70 / 90 / 110 (+0.25 per Ability Power) per second

    This spell is Karthus' early game laning tool and late game DPS tool. Early game, you will only need 1 point in this to start gaining mana on every creep kill. Late game, maxed out, it makes everything around you run away like little girls getting sprayed with a hose. Inbetween those times, do not use it. Why? It eats wayyy too much mana to keep up, doesn't do worthwhile damage, and you are not ready to go suicidal just yet by standing directly next to your enemy while he beats your face in and your defile lightly tickles him. That is for lategame, when you will be in the thick of the teamfight and have a good reason to be right up next to your enemies. Also Farms creeps lategame like a boss with Lay Waste. When you die, always activate it so anyone dumb enough to stand around your corpse will eat around 1000 damage before dropping like flies. This is the third ability that sort of makes Karthus, Karthus.

    (Active): After channeling for 3 seconds, Karthus deals magic damage to all enemy champions.

    * Range: Global

    Cost: 150 / 175 / 200 Mana

    Cooldown: 180 / 150 / 120 seconds

    Magic Damage: 250 / 400 / 550 (+0.7 per Ability Power)

    And the moment you've been waiting for, ladies and gentlegerms. The granddaddy ult of the them all that has killed every single one of you at some point or another. The final ability that makes Karthus, Karthus. A mapwide big damage nuke, great for killing off those pesky runners who think they will make it back to fountain before they die, while you laugh heartily into your Death Note/Mejai SoulStealer. I will dedicate a section to this later.

  • Masteries + Runes

    I run a 10/0/20 Mastery Setup on Karthus


    for runes, I run:
    Greater Quintessence of Fortitude OR Greater Quintessence of Insight
    Greater Mark of Insight
    Greater Seal of Clarity
    Greater Glyph of Warding

    Magic Pen, Mana Regen, magic resist (to keep your butt safe from those nukes) and some health to help you dominate the lane. You can throw in more magic pen runes, but I find this runeset to be the safest overall without going too overboard.

  • Skilling Order

    Karthus has a pretty straightforward skill build: Focus on Damage, Damage, and more Damage,

    Like I stated before, leveling up Defile second is a waste until you have the mana from an Archangels to sustain it indefinitely, which comes much later on. The slow, armor/MR reduction, and wall size increase per level is greater than the meager damage you get from Defile. Plus, your AP scales with defile, letting it doe more damage anyways. Lay Waste is all the damage you will ever, ever need. Wall is too precious to not get until lategame.

    tl;dr, Defile is overrated, get points in Wall.

  • Summoner Abilities

    Karthus is an offensive caster, so thus:


    Ignite gives you bonus early game AP plus an extra nuke to finish off those runners, or harass the enemy when they pop a potion, negating their heal. Really it's just an extra nuke for your already deadly arsenal.

    Ghost is your offensive and defensive spell. You will use it to rush down people in lane and scare the crap out of them. More on that later.

    Other good spells include:

    Flash Good to escape and to never die in laning, a favorite of many champions.

    Teleport Lategame Karthus can farm minions in seconds, letting you suprize push any lane to their tower instantly. Earlygame a teleport to whatever lane you wish for a gank/push is always a good thing.

    Do NOT use:

    Clarity Do not take this on Karthus. If you need Clarity earlygame, you either A) Don't have the masteries/runes for mana regen, or B) you can't last hit and give yourself more mana through killing minions. Stop spamming lay waste until your mana pool is empty and you will learn to manage your mana, which is a helpful skill all around. If you don't have runes, sure, take it. Otherwise, learn to play. Really.

    Clairvoyance You already have a free clairvoyance with Wall of Pain, this is just redundant.

    Exhaust You already have a slow, this is also redundant.

    [spell=rally] Why would you do that.

    Revive Revive on a god of death? So fahanny joke. Use only for dicking around. Death Defied is all you need when you die.

  • Items

    Stop, build time.

    Starting items:

    Doran's Ring + Health Potion

    Core build:

    [item=Banshees Veil]
    Sorcerer's Shoes
    Rabadon's Deathcap
    Rylai's Crystal Scepter
    [item=Zhonyas Hourglass]

    Against Enemies stacking Magic Resist:

    Void Staff

    Against Enemies Not Stacking Magic Resist:

    Abyssal Scepter

    For Survivability:

    Banshee's Veil Against Magic Heavy Teams

    Other Worthwhile Mentions:

    Archangel's Staff
    Will of the Ancients
    Mejai's Soulstealer



    First Item, Always

    [Rod of Ag-- NO, NOT ANYMORE.

    Catalyst the Protector
    This is the key reason 99% of players do not play Karthus correctly. Almost every Karthus in a goddamn world feels the need to rush archangels on Karthus first when he does not need that much mana that early and there are much easier ways to gain AP and other useful stats, such as BLOODY HEALTH.

    Karthus is a medium range caster with little CC or escape methods. He is a especially squishy caster, and a caster that supplies his damage in damage over time, or DPS. That means if he can't survive long enough to get 3 Lay Wastes and his Defile damage in, he is as good as worthless. Survivability is critical on Karthus, as his natural damage is already crazy high, he simply needs the time to survive to dish it out. This is why we buy The Rod. The Rod as it shall be named henceforth is what sets the smart Karthus players from the free-weekers.

    You should always rush a Catalyst before or after your Sorc Boots. This gives you laning health and mana so you can supply more Lay Wastes. From there, you can get a tear, BUT NOT AN ARCHANGELS. Once you get the money to finish The Rod, you may then begin the AP stacking in any form whatsoever. The health from the Rod should almost all of the time keep you well alive until lategame, where we can farm up any item you please whatsoever.

    Sorcerer's Shoes

    Pretty self explanatory.

    Archangel's Staff
    A great item on Karthus. AP is godlike, and the passive synchronizes with The Rod. Gives us plenty of mana to farm with and unload nukes with too. Should almost always be bought on Karthus. BUT NEVER, EVER FIRST. Archangels on Kassadin works because he has the escape to not die with. Karthus is not a champ you want to glass cannon it up as. Keep the archangel rushing on mages with escapes.

    You may buy a second one lategame depending on conditions. The ap gain is pretty big, expecially with rod of ages, so it all depends on what exactly you need.

    Rabadon's Deathcap
    Ooooooh boy, the deathcap. This baby combined with archangels lets your AP pierce the heavens of limitations. Absolutely grab this item if you wish to do damage lategame. It is not so important until you grab archangels and The Rod, but important none the less.

    item=Rylai's Crystal Scepter]
    Survivability and AP wrapped in one, a good combo for Karthus. Absolutely crucial on Karthis, as it keeps your targets within your Defile and unable to dodge lay wastes as easily due to being slowed and all. The health helps your survivability as well. Lets you chase, kite, and be an annoying twat. Use in conbination with your ult to help your team chase anywhere on the map at any time!


    Void Staff and Abyssal Scepter

    Every mage at some point in time has to deal with magic resist. It is a simple fact of life. A fact that is usually overcome with about 2500 gold. But where to spend it is key. MR stackers (Banshees, Force of Nature, Mercs and Spirit Visage) should be dealt with ASAP by rushing void staff. It will pierce through most of their MR and will let you continue dealing damage. Should they not stack MR, grab Abyssal scepter. It will usually drop their MR to 0, letting you dish out unheard of amounts of damage. Nearly 600 a pop from a Lay Waste should drop any carry stupid enough to get near you.


    For Survivability:

    Banshee's Veil
    Obvious choice. Health, mana, MR, and a spell block. Keeps them CC's off you for a bit and gives some survivability.

    Zhonya's Hourglass
    A new item added to the mix, this nice item gives us a nice chunk of armor and AP along with the well known Zhonyas passive. Grab this if you find yourself vs a physical heavy team. The active on this will keep you safe and sound if you find yourself focused in a teamfight, while your defile eats them and your team beats them down.

    Experiment with other items, such as Sunfire Capes and such. Hell, even Warmogs. Ok, maybe not Warmogs.


    Other Possibly Worthwhile Items:

    Will of the Ancients
    Spellvamp is an interesting stat that while worse than lifesteal might keep you alive in a teamfight. 15% healing off of your 600 damage nukes is ~100 per hit, plus your defile gives you about 30 HP/s. Not amazing, and I usually would not recommend it, but experiment a bit. If you're not particularly focused and nuked in seconds this might just keep you alive throughout the fight. Also lets you regen on neutral creeps when low.

    Mejai's Soulstealer
    If you are wrecking faces early, or getting lots of assists from ults and whatnot, grab one of these if you wish. Snowballing is always fun. Otherwise, stay away from it.

  • Build Example

    This is an average build for me in a game where we are winning heartily.


    And this is a game versus some tough caster opposition.


    And this is versus some hardcore AD champions.


    Mix and match items for your desired Karthus.

  • Requiem

    Karthus' Ult in a Nutshell:

    External Image

    This will be the majority of your playtime with Karthus, and most likely the reason why you picked the guy in the first place. Your ult is a hilarious champion farming tool from anywhere at any time that absolutely noone sees coming. But it has a few nuances for being a simple nuke due to it's global nature, which I will outline below.

    So first off, what you do at level six. You check the map and see the health of everyone around the map. You need to keep your eye focused on the enemy teams health bars at all time in lane. Usually, you can rely on your teammates to point out when to use your ult to save you the time, but you must scrutinize their call for ult, as it might not be the right time to use one. There is a few steps to determine if it is smart to use your ult.

    First: The damage. At lvl 1, Karthus' ult does 250 damage. That means if the enemy has 2 and a half bars left, you earn a kill. You can add on your AP and the damage from subsequent levels as well. Always know how much damage you're packing and what health they have left. However, it is not yet time to ult. That leads us to step 2 of the analysis.

    Second: Their mitigation. More specifically, MR. Usually by the time you hit lvl 6, champs on the sidelanes will have an average of 30 MR naturally. This means that your ult, while having 250 damage, will only do about 200 after calculating resistance. After they go back to base and buy items however, msot players will itemize against you. Seeing a heavy damage caster on the enemy team, most champs will grab Merc treads, boosting them up to 53 MR. Players these days often run MR runes as well, so they can have resistances as high as 70 by 10 minutes in.

    Note: Also factor in if the enemies have shields. Champs like Shen and Rammus, while appearing to be weak enough to be killed by a finishing requiem, can activate their shields at a moments notice and eat the damage from your ult. Many other champs have abilities like this, so it's helpful to expect what will happen if you try to take them out. Know your enemy is what I'm saying.

    Third and last: The timing. "KARTHUS ULT" is something you might hear often, just as your ult is going off cooldown. However, be wary if you do not ult within 5 seconds of your teammates telling you to do so. Your opponents could have easily teleported back to base, or even healed in that timeframe. If your enemy has entered the fog of war and you can't check their health, consider that saving your ult might be more helpful than whiffing the ult, and having another opportunity to kill come up a few moments later. It is always a gut choice.

    After the early laning game however, you can be more liberal with your ult. Use it before a teamfight to weaken the enemy team, and so that you aren't stunned in the middle of the fight while channeling and not getting it off at all. Use it when you die in a teamfight to nuke their entire team after you throw down a wall and put on your defile. You have no mana costs while dead, so abuse it. Lategame your ult is just another nuke once teamfights start, so consider using it before or after you die.

  • Whats gonna work? TEAMWORK!

    So now the big question: Whats a Karthus to do when the teams start the clashan' and the brawlan' and the hurtan'? Well, Karthus is quite unique in his role. Karthus is an AP champ to balance out the damage on your team, but he is not the bursty, nuker mage champ made to one shot enemy champs. Rather, Karthus is an AP DPS carry, basically an AP version of Corki or Miss Fortune. Karthus CAN kill enemies very quickly, and is made to lay down quite a beating, being able to out dps many champs in this game with the simple click of Q. Other than being your stereotypical damaging champion-eating carry, he has a few unique tricks he can pull in a teamfight to give you the edge to win.

    Like stated before, Ulting before the teamfight starts is usually your first job. This takes roughly 500+ out of the enemy healthbars before the battle, giving you a free advantage before the fight even starts, letting you clean them up easily. However, should you die before using your ult, using it while you are dead is also a good decision, as it is un-cancellable and most of their team will be dead or dying after your team wails on them, usually neting you 1 or more kills at least.

    Your second and most important utility in the teamfight is wall. Landing your wall can decide a teamfight. Landing the wall on multiple enemies slows the shit out of them and reduces all of their armor and MR for 5 seconds. It's free kills everywhere. However, even if you can't land the wall on top of all of them, it simply being there can make all the difference. It can split teams, prevent people form running, and prevent chasing. The psychological impact of the Wall is not to be underestimated.

    Your third best utility is dying. Dying at the focus point in a teamfight can make a huge difference. Imagine fiddlesticks crowstorm for 8 seconds in 1 chokepoint where your team has the enemy pinned down after you have died, and an uncancelleable ult and walls and lay waste flying everywhere. Deciding where you will die can take the heat off your team while you are focused and let you continue being a pain in the ass from the grave. The enemy team has to make a choice whether to split up, or stand near your corpse and die, usually either one deciding the teamfight in your favor,

  • Creep Jungling

    External Image

    Like I say in many other of my guides:

    The infinite mana means you can spam all day everyday on your spells, which means you can build up your archangels in mere minutes. The cooldown is also helpful for your wall and Requiem. Granted, if you have a more mana hungry champion, like Anivia, op to give it to them first. but you are a caster, first and foremost. Golem is your prized possession, and try to grab it whenever possible and your teammates don't need it.

    HOWEVER: If you have someone else on your team who is very CDR/Mana reliant (Amumu, Fiddles, Anivia), stop stealing their goddamn buff. Yes you are a wild bull with blue buff but they can use it that much more effectively.

  • Credits

    Still have a few things to touch up on, will fix when I get around to it. This guide has a few more things in store for it soon.

    No updates yet.

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