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Karthus Build Guide by Hullos

Middle 2.4 Million Mastery-Lane Karthus Guide-Season 11

Middle 2.4 Million Mastery-Lane Karthus Guide-Season 11

Updated on September 22, 2021
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League of Legends Build Guide Author Hullos Build Guide By Hullos 45 7 178,421 Views 6 Comments
45 7 178,421 Views 6 Comments League of Legends Build Guide Author Hullos Karthus Build Guide By Hullos Updated on September 22, 2021
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Runes: Dark harvest

1 2
Domination
Dark Harvest
Taste of Blood
Eyeball Collection
Ultimate Hunter

Precision
Presence of Mind
Last Stand
Bonus:

+9 Adaptive (5.4 AD or 9 AP)
+9 Adaptive (5.4 AD or 9 AP)
+6 Armor

Spells:

1 2 3 4
Mid 1
LoL Summoner Spell: Exhaust

Exhaust

LoL Summoner Spell: Flash

Flash

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Jungle Role
Ranked #26 in
Jungle Role
Win 48%
Get More Stats
Jungle Role Ranked #26 in
Jungle Role
Win 48%
More Karthus Runes
>

Ability Order Ability leveling

Threats & Synergies

Threats Synergies
Extreme Major Even Minor Tiny
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None Low Ok Strong Ideal
Extreme Threats
Ideal Synergies
Synergies
Ideal Strong Ok Low None

Champion Build Guide

2.4 Million Mastery-Lane Karthus Guide-Season 11

By Hullos
INTRODUCTION
I play Karthus, a lot of Karthus. I may not be any challenger mid player, I got diamond for a while with Karthus and I was diamond last season but decayed after playing Valorant for 2 months and ended in plat one. I have 2.4 (old MP picture) million mastery points on Karthus and play way too many normal games for my own good. I may not be able to tell you how to get to challenger, but I might be able to tell you how to build and play Karthus.
Regarding Most Recent Buffs and item Changes

MOST RECENT KARTHUS NERF

The recent 10 flat DMG at later levels nerf while not unnoticeable is far from the worse nerf Karthus could have gotten. The only time you will feel the nerf is around lv 9 when you max out Lay Waste but don't have too much ap yet.

NEW IETMS AND RUNES

The recent nerf to Dark Seal is small but does move the starting item more to Doran's Ring either way it is not a huge change just a bit worse when ahead and also worse when you die.
Pros and Cons and Quick Tips

Pros


-Versatile builds and play styles
-low skill floor and high ceiling
-great carry potential
-High damage
-Great in team fights

Cons


-quite a few rough match ups
-needs to hit a lot of skill shots
-no mobility
-little utility

Tips to keep in mind when learning Karthus


There is no one best build, no build that you will build 100% of the time. People may try to tell you what build is the only good one but they are almost always wrong. There can be a build you feel most comfortable with and that is fine, but all builds have their uses in certain situations. Karthus is deceptively versatile in builds. I encourage you to play and try different builds. Some of them will surprise you at how well they work.
Your play style will change based on build and lane match up. To play Karthus effectively you will have to learn new play styles e.g( poke, aggressive, safe,). Often you will be switching mid game depending on items, levels, and how strong you are. Make sure you don't lose a lead by not adjusting play styles. This will also apply to builds as you might have to shift what you are building to go into a fast Zhonya's Hourglass or Void Staff.

Karthus is not always a "just press R champ" there will be games where your Requiem will be almost useless and you will have to play well with Lay Waste and positioning. Same goes with "abusing passive", don't go flashing in every fight. In reality there are few times where you will need to do that. Often you will be playing like a zone/artillery mage.
One of the most important tips is that just starting out, you may feel useless outside of pressing Requiem and Death Defied. A lot of the skills you need for playing lane Karthus are gotten from playing him. I cant tell you how to hit Lay Wastes, you learn by playing. Once you start to get good you can start to duel any lane opponent much easier. Also something important is that different people will find different match ups hard, I find Malzahar to be super easy but you may find it hard. My match up list is not the be all end all. Also depending on rank the match-ups can change considerably.
Summoner Spells
GOOD
One of the two main summoner spells for Karthus mid/top, Though of the two Exhaust is the more popular. As a basic rule I like to follow that works most games is if the lane opponent lacks a good way to escape a trade or all in than this is most likely the better option. This also, opposed to barrier, does offer some kill potential.

GOOD MID
The other of the two main spell though this is basically only taken mid. As opposed to exhaust, this is for opponents that can get out of a trade for free such as Yone. barrier is up more often and is better against quick burst champs on short cooldowns. While it does not offer kill potential it does serve as great bait when you are low and the opponents forgets you have it.

GOOD BOT
If you are going bot you basically always take this. Though if you have a duo and want to be aggressive Exhaust can also be good.

EHHHH... MAYBE
Only taken top lane as not to set yourself even further behind as you already have for picking Karthus top. While not great it can be taken mid though I almost never have found that useful over say Exhaust.

BAD
This is almost never taken unless you feel like going absolutely crazy on your lane opponent. The problem with Ignite is that if you are close enough to use it the Opponent is almost certainly already on top of you and in that case you want exhaust or barrier. Also, in late game, you are almost always in the back line and will find it even harder to use.
Runes and other Options
This is the rune page most player go with and for good reason. While not as good in lane as Summon Aery, partially because of the 0 base healing on rav hunter, this rune does make it so you will almost for sure do dmg no matter how much you int, as long as you get the DH stacks. Also offers up the just press R play style with ult hunter. If you are starting out on Karthus this is most likely the better pick for you.
This is a lane focused rune page as it offers much better poke in lane and better mana sustain. Though, even with gathering storm, will often feel worse late game. If you need a lead in lane this rune page will be better for getting it but you need to play a bit better to keep the lead.
Finally riot gave rav the hard nerf. With this nerf it makes the domination tree much less appealing. While the taste of blood healing is still there and later on rav will still heal for a decent amount, it will be noticeably less. with the removal of any base healing this rune feels bad if you get behind. Though overall I still think this rune is a viable choice just into teams who have some poke in lane or late game.
With rav hunter nerf this rune has finally come into the spotlight a bit. I think Karthus will now take this over rav hunter into low poke teams or in jg. The haste on ult can feel real nice on low ability haste builds like ludens pen.
Many people will argue between witch of the two are better, both are great and help a ton. While Last Stand will often do more dmg, Coup de Grace will allow you to execute low enemy's securing kills. test both out or chose depending on which fits you better. In the end no Karthus rune page will be without one of these.
This is a rune that will change game to game. Gathering Storm is the clear option for scaling into late and will be the pick if you see the game going past 30 minutes. Scorch is for the lane bully, if you are against almost any melee champ this rune can be very helpful in order to prevent engages with poke, assuming you can poke them.
This rune was nerfed hard in the new item update. It no longer gives permanent max mana, but instead mana regen on hitting an opponent. While the mana restore on takedown is still there and still very good the rune is for sure weaker. Though with tear still being a pretty bad item the rune is still a basically must have.
This rune is taken if you are using the aery rune line. nice to have as it basically makes sure you don't run out of mana as POM and a mythic is not always enough.
Ability Haste for free is nice and this rune will still be used though the third part of the rune we can not use.
Easy sustain in lane, this rune grants a surprising amount of healing over the duration of the game. The other two in the tree Cheap Shot and Sudden Impact are either not usable or not used enough to consider running.
Pick your poison, all grant you 30 AP, just figure out which one you are going to stack the fastest or most reliably.
NEW ITEM AND BUILDS

STARTING ITEMS


ALSO SEE THE STARTING OUT PORTION BELOW THIS SECTION FOR A QUICK OVERVIEW OF THE RECOMENDED STARTING OUT BUILD.



Currently not good
This item right now is in a weird spot, it is forced if night harvester ever comes back but kinda sucks. If you take a mana mythic best not start this item.

Good
This item is good for mana and helps you be aggressive in lane, Though might present some mana issues if you are not carful. If you starts a mana mythic this is the better choice.

SITUATIONALLY GOOD
While I don't take it often first item, it is still good. I buy it when I am already ahead or feel strong. But more often in the ludens build. If you want to start it over Doran's Ring, you can, just be extra carful with mana.

SITUATIONALLY GOOD
When you want the aery rune but still want sustain this can be great. Also is better with the loss of base healing on rav hunter. You lose a bit of all in pressure but helps with poke over time.

MYTHIC ITEMS


BAD CURRENTLY
The item is cool in theory, but with the lack of mana, it become a hard sell. Having to build tear right now is a detriment, so that kills the item almost singlehandedly. also Luden's Tempest offer mana and pen even if its bust is a bit worse.

GOOD
This item is the go to item for most players. The amount of damage its burn effect can do on karthus is just ridiculous. Not to mention the extra damage vs tanks. this plus the mana and ability haste, is just a perfect item for karthus.

BAD CURRENTLY
This item did see some experimentation at first but since has fallen completely out of favor. With a recent change that lowers the omnivamp and removes the pen the item only becomes less useful on Karthus. Until the item sees changes do not take this item.

EHHH... MAYBE FOR FUN
This item is kinda cool but lacks a large enough amount of ability haste and reliable DMG. While it does give you AP for every legendary it still cant compare to the DMG of even Luden's Tempest or any other mythic for that matter. The passive, while cool, is unreliable and only lasts 1.5 seconds so with low ability haste around 1 Lay Waste and that's IF you hit the active. Though it does not need to take tear witch is a up side.

SITUATIONALLY GOOD
This item has seen some changes recently in the form of a CD reduction mechanic on Echo. This is a decent buff for the item on Karthus as his E Defile can reduce the CD fast. In tandem with the anguish changes this item is, for now, not the go to for low tank teams. Matched with an early void staff or soul stealer early can make this item destroy squishy targets.

MEME BUT BAD.... STILL FUN THOUGH
This item has started to appear as another option for Karthus for a bit as a tank route but the item has seen some nerfs. Though in my testing it is not awful if the team needs a tank. You will still do decent late game DMG but in early and mid game you rely on your team to deal DMG so make sure you have some before you build this. I think this build is still a meme build but can be fun to build and may be viable in the future.

LGENDARY ITEMS


GOOD
Basically a legendary item. I recommend getting these right after or before mythic item. Though I often get then before any mythic components if I have the gold, as 18 flat pen will be a lot more dmg then 40 ap on karthus. Its a great way to try to get a lead in lane and the movement speed is just icing on the cake.

CURENTLY BAD
While karthus loves using mana you need to avoid this item. The item not only builds out of tear, a bad starting item, but also is not worth it for the stats it gives. It only grants big ap numbers and mana. With no haste or pen and anything the item feels awful.

SITUALTIONALLY GOOD
If the Dark Seal you bought ends up getting some good stacks, there is really no reason not to upgrade it. on the ludens build it even gives a cheap legendary item for 5 free flat pen. Though late game you will die more so you will most likely end up selling it.

GOOD
This item is very solid for Karthus and is always an option in any build. This item with Liandry's Anguish feels like a crazy power spike and guarantees you at the top of the dmg charts. in addition it grants lots of HP and resistances. The only issue is, it is in competition for second item, which usually has tough contenders like hourglass.

SITUALTIONALLY GOOD
This item got a nice buff to its grievous wounds(GW) and ap effect but in turn lost any reason to build it if you don't want GW. Its component lost the flat pen and so did the item. But for less gold and better GW the item will still be used. With the amount of healing in the game as of writing this, you will end up building this a lot.

KINDA DECENT BUT HAS TOUGH COMPETITION
This item got some small buffs in an extra 10% slow and 50 HP but the extra 400 gold cost and the fact that it no longer combos with liandrys makes it a hard sell. This item I don't see being used unless you want the hp and find group team fights often. Can be used as pick potential but if that is your job you have bigger issues in the game. Though if for some reason you need another item and you don't need GW or Void then this could be okay but unlikely.

GOOD
This item is a must in most builds, at times even first item. The component Seeker's Armguard did get a nerf a bit ago but it is still good to build early. hourglass is too good to pass up as an item as a whole.

SITUATIONALLY GOOD
This item was good mainly due to the component being great into ap losing lanes. Though with Verdant Barrier nerfed I think this item will be build less Though it can still be built against ap lane opponents. Thus the item will still be used and still does decent vs heavy ap teams. Not to mention the spell shield feels nicer than you would think.

SITUATIONALLY GOOD
This item is weird. It is a huge power spike no mater when you get it. There is one problem though. When you start to buy the item, if it takes too long, you could lose your lead or fall behind due to how long it take to get it. So consider buying it with care, I recommend going for void or GW before getting this item if they are needed.

GOOD
The it is an anti-take item... but who cares because it also basically gives you true damage vs squishy targets as well with boots. It only get better in the ludens build so much so where you build it second often.


Builds - lots of words




[*] Anguish anti-tank DPS (best build ATM)

Due to the nature of this build you will want to be in fights longer to maximize dmg, thus aery often does better in this case. Aery also can often out dmg Dark Harvest also better at getting you ahead to the Liandry's Anguish power spike. Dark Harvest can be taken still but I prefer aery most time with this build.

Playing lane


One major plus of this build is the fact that you don't get Tear of the Goddess due to manaflow and the mana and anguish. This means that getting Doran's Ring and having aery means you gave a ton of early pressure for poke. While you are still prone to assassins, if you poke properly, you can prevent the all in. The core of the build is Liandry's Anguish and Demonic Embrace, the two items together grants tons of over time dmg that if play properly can end up doing upwards of 25k dmg together over a game. Then paired with hourglass means you can survive dives and stay alive longer plus becoming even more tanky with demonic' s passive. Then finally with the anguish passive and a potential Void Staff you can deal with tanks great you might even have room for a deathcap if you don't need anti heal. The main weakness though is the lack of sustain without Ravenous Hunter. Doran's Ring does a serviceable job in lane but late game it can become a bit problematic HP wise. That is why it is even more necessary to play back and safe to maximize dmg till the time is right to die.

When to run this build


This build is now the best build for lane and JG (jg taking DH though). It works in any scenario against any team. Only Luden's Tempest when into an entire no tank team can outperform it. The lots of dmg along with antitank mana and solid ability haste makes this build the way to go.



[*] Ludens Full Pen

Of course when you hear full pen you are taking Dark Harvest. Though along with all of the basic runes you will want to take the ability haste passive rune as the build only gets the 20 from ludens and is stuck on that till you get Zhonya's Hourglass.

Playing lane


This build in lane plays aggressive as your main goal is to get a lead, ask for ganks and play to your lead. Of course Doran's Ring is a must in any aggressive lane. On first back you have a few options, first, Dark Seal is a great first back with other components towards Lost Chapter. but if you can buy the full chapter don't let the dare seal get in the way of that. You can take Barrier but overall Exhaust is going to be more helpful to get kills and since you take this into a team that is all squishy the likely hood that one opponent will get fed and and needs to be exhausted is high. If you don't get a lead in lane make sure you keep trying to stack the Mejai's Soulstealer as Requiem is great at getting assists. In order for this build to work best the more stacks the better. Going into mid game is when this build shines, if you successfully get fed you can pop any opponent as the backline mage karthus always wanted to be. That also means that the run in and int playstyle will not work here as stacks are very important. Of course when the time come you might have to int but this build with do it much less than other builds.

When to run this build


As is said before, this build works best into no tank teams. This is the same as Night Harvester, The only difference is playstyle preference. If you can play like a backline mage effectively then this build with over all be better. Also its best to take this into a lane opponent you are confident you can win against. otherwise its best to go with anguish because that way you are useful no matter what even if you lose lane.



BUILDS BELOW THIS LINE ARE EITHER MEME OR NOT CURRENTLY VIABLE





[*] Night harvester tear

The rune page to take is the classic Dark Harvest with precision secondary. You will have Archangel's Staff but even so Presence of Mind is still very helpful as in long fight you will still run out of mana. It also keeps you in lane longer mana wise. Of course the DH proc with Night Harvester is disgusting and can pop ADC's if they are not dead already. The goal for each fight with this build is to kill the squishy targets and that's what this rune page does.

Playing lane


While this is the big DMG build the start of the lane phase will be mostly passive on your part. This is because you are forced to start tear and lose a majority of pressure in lane. Though killing the opponent is not out of the question with some good poke before a fight. At first back hopefully you can buy a Hextech Alternator, this item is great and gives a large spike in kill potential. Keep in mind that you are still squishy and have low HP. This means that while you will mostly be taking Barrier or Exhaust without extra HP from Doran's Ring and the ideal first back item also giving no HP most lane opponents can kill you in the 1v1 if you don't poke well before the engage. You will start to realize that poke is a large part of this build as the passive of Night Harvester provides so much of it. Not only are you just as squishy as before the new items but most other champs also got more DMG. But the same applies to Karthus, this means that it is more important than ever to play like and artillery mage for as long as possible till you actually need to die, of course make sure you die in a useful place. This makes sure that you get the max amount of damage as possible. Abuse the passive of Night Harvester and its movement speed to reposition after a procing it.

When to run this build


This build is nice but even so mainly is only taken when the opponents team has no tanks. It can obliterate squishy targets but fails to do meaningful dmg vs tanks and bruisers. Though in ADC this build becomes a bit more possible as you can guarantee fighting one squishy target.


[*] RiftMaker Sustain - for fun build

Dark Harvest in an attempt to make up for the loss in DMG with this build and Ravenous Hunter to add on more omnivamp. Just the basic rune page lines up well though sorcery could be taken to use Absolute Focus and another dmg amp rune although Manaflow Band would most likely be useful as karthus might need more mana than tear can provide at some points with this build.

Playing lane


This build in fact has less DMG than most previous karthus builds with old items and on top of that less healing even with the omnivamp from Riftmaker. While it can be nice in lane as a first back item Leeching Leer the lack of ability haste makes it have a TON less DPS than other builds. This means that other builds due to increased DMG might out heal this build just with Ravenous Hunter. While the passive is cool, surviving to have it at max stacks is difficult (that's part of the reason demonic embrace is part of the build so the burn keeps you in combat). Even the true damage is lack luster without the dmg to back it up with such low ability haste. You could take Cosmic Drive to mend that problem and get some MS but to build another item just to make ends meet is not ideal. The upsides for this build is that in lane it is the safest build with the most sustain. Thus being the safest lane you can take Teleport and not get killed. Also with the Liandry's Anguish nerf it now has higher %pen for later in the game, but it still takes forever. The last good thing I can think of is that this item would feel solid into assassins and other bad matchups like Vladimir. Beyond that this build will be mediocre until maybe a tested tank karthus comes to fruition.

When to run this build


This can be taken into tanks but even then Liandry's Anguish is still better. But the main thing to take this item into is into unfavorable matchups like I said Vladimir and Kassadin. The build helps you survive into assassins matchups but does not help you deal DMG later, you will be better off building Seeker's Armguard.
Just Starting Out Quick Guide
When I just starting out on Karthus, all of this information can get a bit overwhelming. So this section is going to summarize what I recommend to take when starting out on karthus for items, runes, and a bit of playstyle.

ITEMS


First Item

In terms of starting items, Doran's Ring is best to start when new to karthus. Dark Seal is an option once you get some experience. for first complete item, while I also believe the Luden's Tempest build is good, the aguish build will always be viable compared to luden's only sometimes. You can take anguish into any team and find success, so starting out on Karthus I recommend that you always go with this build path. Generally you finish boots right after this item.

Second and Third Item

Second item has quite a few options but for simplicities sake, I am going to narrow it down to just two options. Starting with Zhonya's Hourglass, in most games you can feel if you will need this item sooner or later, either way you will be getting it. If you are getting ran at by the enemy assassins or frontline, and they have the ability to kill you. You might want hourglass... obviously. Demonic Embrace is the option I go for more often, this is due more to my playstyle. This provides not only solid damage, but also good protection in hp and resistances. So as long as there is not crazy fed carry on the opponent team this should be good enough protection for second item. But the main determining factor is how you play. Do you like to run in and die in the middle of the enemmy team? hourglass. Do you like to stay a bit back and try to maximize damage? demonic. The third item should almost always the one you did not take second.

Forth and Fifth Item

Personally I almost always go Void Staff here. But in the case where they don't have a tank, Rabadon's Deathcap can also be taken here. Void staff can also be taken third item if you feel if you don't need hourglass at that point either. Void staff is recommended here but if the opponents don't build MR and you have the gold, deathcap can be great. The fifth item should almost always the one you did not take forth.

Sixth Item... Kinda

THIS ITEM CAN BE BUILT AT ANY TIME DEPENDING ON THE NEED FOR IT this item will almost always be in your build due to how big healing is right now. Generally though I just keep the item component till sixth item and then upgrade it when it the last item and boots need replaced.

RUNES


Main tree

I'm going to be honest, I love the Summon Aery, sometimes more than dark harvest. But when starting on Karthus, you will mostly likely suck like I did and heavily rely on ult damage. Dark Harvest makes that playstyle much more effective. This also gives you access to Ultimate Hunter so you can ult more. Also the page is more beginner friendly as you get healing access, where as aery does not.

Secondary Tree

The precision tree is in every Karthus rune page with basically no exceptions. Presence of Mind provides necessary mana help and the solid damage of Last Stand. Now some people will tell you to go Coup de Grace, but starting out you will die a good amount most likely. So you will get much more value out of Last Stand.

A BIT ABOUT PLAYSTYLE

While I do not like the run in and die playstyle, starting out with it is a great way to figure out if you like it and get an idea of good times to int into the enemy team. To maximize damage with Karthus it take a bit of getting to know the positioning and kitting required. A lot of the skill required for Karthus beyond hitting skill shots is positioning and kitting. Its almost as if you are playing ADC with a suicide button. I found that ADC players can often be good at Karthus positioning and kitting but find the skill shots difficult. I recommend that you start out playing Karthus looking for times to run in and die, then slowly transition into a back line karthus who knows when to run in and die. Over time you should die less and less as karthus.
Other lanes - ADC - Top
TOP LANE KARTHUS


Top lane is the least played role for Karthus, that he can be played in, and for a few reasons. Now more than ever, with ROA gone, top lane becomes more difficult to play. Even if you do take the new Leeching Leer you still will not have the DMG needed to play late game. Even with that item, without Barrier or Exhaust you still might get destroyed if you don't position perfectly. Not to mention most likely you will be fighting some heavy engage bruiser that Karthus struggles so much against. With Tanks, being Karthus's best top lane matchup most times, becoming stronger, them now being able to kill you, that only leaves ranged top lanners as a safe pick to play karthus into. At the end of the day never pick karthus top blind.

ADC KARTHUS

ADC Karthus on the other hand is almost if not just as viable as mid Karthus. Having a support can solve a lot of problems for Karthus and help him make use of early game Lay Waste damage. Though the supports that go well with Karthus are limited, most of them are listed in the synergies tab, they work incredibly. The average shield/heal Support like Lulu is far from the best choice to run with Karthus. But any engage support will work wonders, the best being Leona, Thresh and Nautilus. Most of the time assuming you have a good support, you will porably be taking Liandry's Anguish as with Lost Chapter you can still play agro. Very rarely will you be playing safe in bot lane unless they pick Lucian Leona or something even more agro than your lane. Starting the new Tear of the Goddess means that even with an aggressive support you may find it more difficult to dominate bot lane thus a mana mythic is necessary to start Doran's Ring. There is also the problem that since you are behind on levels and Karthus relies heavily on ability damage you will do slightly less damages than normal.
The late game plan

Pointers on playing late game


While yes Karthus is a late game champion, but he is not as strong as many think. By the time late game rolls around yes you may have 1000 AP, depending on the build, but everyone in the game will almost certainly have a way to survive your Requiem. Weather that be a Zhonya's Hourglass of their own, the supports heals/shields are just as strong as Requiem or they are just a lot more tanky than mid game. Not to mention the countless other ability's. You will start to see that unless you play like a god, you will almost never have enough damage to carry hyper late game as it becomes harder to get the damage off. Keep this in mind going into the next point.

Late game means that inevitably, there will be a lot of team fights. In team fights too many new Karthus player think the right play is always run in like a madman with Defile on and die, this is not the correct play style for late game. Yes there will be times where that is the correct play, but it does not happen often and most certainly not every team fight. I cant really describe when to flash in and die, but a lot of factors come into play, to name a few: has someone else engaged? How many people are close together? Can the team follow up? Can the enemy team get away? Do you have Zhonya's Hourglass up? Instead of going for the all in play all the time, play more like an artillery mage to maximize you dmg and act like a final line of defense for the ADC.

While in mid game you may have been able to kill anyone you wanted, especially when you are strong, but in late game prioritizing the correct targets is essential. Even if you are late game you will do meaningless dmg to the full tank Dr. Mundo. Since you play like and artillery mage you can aim for the ADC, or other high dmg targets, and with Wall of Pain potentially catch them out. Even when you flash in make sure you are going for the highest threat target. This should be done at all points in the game but becomes even more crucial at late game.
A Few Cool clips I had Laying Around
OLD ITEMS AND BUILDS

IM KEEPING THIS HERE JUST IN CASE RIOT RE-DOES EVERYTHING SO I DONT HAVE TO RE-WRITE IT.


The main item for mages, and while this item is very good on Karthus for just doing lots of damage we have other options as well. This item grants mana damage and gets you to the minimum 20% CDR necessary for Karthus. You will be taking Dark Harvest with this item almost every time.
This item on paper seems insane on Karthus, and it is good, it is not as good as people lay it out to be, at least not on its own. This item is for when you are going to play safe and sustain in lane. But even though it grants HP Health and mana, it grants no CDR and not enough dmg. That's why this item is almost always paired with Archangel's Staff this item fixes all the problems of ROA. The only downside being it delays the power spike so the build is only used when you know you will get to late game.
This item is often paired with Rod of Ages, but can be build on its own to hit a smaller power spike earlier, often allowing you to build Liandry's Anguish second item.
This item is incredibly strong on Karthus and would be put into almost any build, the only thing stopping it being it offers no CDR and no mana. but many builds such as Archangel's Staff rush and the no mana item build seek to solve those problems to use this item, that's how good it it.
basically the only boot you will ever buy unless you are going the tank-ish build. Great magic pen and a great early buy.
This item is built in most builds in one way or another as magic penetration is very good. One key thing is that if the enemy team does not have heavy healing, it it a better idea just to keep the Oblivion Orb and go to the next item.
Obviously a great item, you build it almost every game in almost every build. The item's synergy with Defile is just great as well as you can throw a Lay Waste right before you activate this item and it will go off when you are in stasis. Of course preventing people from diving on top of you is always great. This item can be build at any point in a build depending on how badly its needed.
This item is good into certain teams and when in combination with Liandry's Anguish can be quite devastating for catching people out or in a team fight. Though I would only recomend against teams with low mobility, and at least a tank or two to get value out of the item otherwise its better to just go into Void Staff or Rabadon's Deathcap.
This item is of course the big damage item, and will be in almost every build even if its replacing boots. Though many players get the item too early, this is a late game item and should only be bought no earlier than 4th item. or else you risk losing your lead or falling behind further as its benefits are less are less the faster you get it.
This item is amazing and built again in almost every build. The only time this is not a good item is if the enemy team has no tanks or even bruisers.
I build the item very rarely and only if the spell shield will be benificail. In almost all other cases Abyssal Mask is better.
This item is used most often in hyper late game to replace boots as your sixth item. The item grants movement speed to compensate for boots and a nice passive to get out or get in to a fight, or just to pop the ADC. Solid item but almost never build other than 6th item.
This item has recently risen in popularity, it has its upsides in certain match ups and can help you dominate a lane even more with better engage. The active is also nice in team fights if you can land it on multiple targets. It would only be built to replace Luden's Tempest but works well.
Both are somewhat meme items but do have their uses. Frozen Heart can be built in with Archangel's Staff for the clean 40% CDR and Sunfire Aegis while you cant proc the passive, it is the best armor item for Karthus that offers HP.

Builds - lots of words



[*] No mana item build

I have mentioned this build many time so far in the guide, the reason being I believe it is one of the best and most consistent builds, while still being versatile. The name makes it obvious but you don't build a single mana item beyond occasionally Dark Seal. The mana all comes from runes like Presence of Mind and Manaflow Band. then in order to deal with CDR you take Transcendence and the 1-10% CDR rune. With mana and CDR covered you can build Oblivion Orb, Sorcerer's Shoes into Liandry's Anguish. these three items create a massive amount of power that spikes faster than Tear of the Goddess for the same gold and keeps kill potential in lane with double pen items. The power though does not fall off and only opens paths for almost any other item needed. this build allows for you to get to necessary items like Zhonya's Hourglass or Void Staff faster. You have the option between Barrier and Exhaust depending on lane opponent.
The rune page you will be using is the second rune page on this guide with Summon Aery, making any personal changes depending on match up. this of course is used for the CDR and mana but also grants a large amount of poke for tough match ups with Summon Aery

Playing lane


Corrupting Potion is the main starting item, or Dark Seal, Refillable Potion. This start mends the lack of sustain the build has health wise. with Ravenous Hunter out you need to start this in order to stay in lane and out poke the opponent. That's how you play lane phase for this build, poke until they cannot engage or till you can engage to win the 1v1. mana early can at times be hard to manage but that becomes better the more you play Karthus and the better you become at farming. DON'T JUST SPAM Lay Waste ON THE WAVE EARLY. punish the opponent for walking up to farm and if they don't need to walk up to farm keep a watch for misplays in positioning, you may be good at poking opponents down but a Wall of Pain with a few Lay Waste's is very possible. With this build once you get ahead you can start to be more aggressive with mana once the runes get stacked, thus playing more aggressively, throwing more Lay Waste's at the opponent, hard shoving or keeping the opponent off the wave.

When to run this build


This build is good against everything to some degree, the main thing this build should not be used against is easy match ups. if you are super confident in lane that you can kill the enemy champion this build is not ideal, but since Karthus does have a lot of bad and even match ups this build exists.


[*] Classic DH luden's


Speaking of ideal verses favorable match ups, this is the build. The items them selves don't look all too different but the runes make all the difference along with Luden's Tempest. With this build you aim to get as strong in lane as fast as possible, even if you die to get the kill, you turn into a weird looking burst artillery mage. with features of both. with Luden's Tempest covering CDR and mana along with Presence of Mind, and Ravenous Hunter with Taste of Blood covering sustain you have all the pieces to need in one item. This build will suffer when against lots of tanks as you may not have the HP or defensive items to live verses them or the damage to kill them, usually you will end up lacking one or the other. But what it does do is one shot the squishy targets and put them to basically half hp at all times with Requiem if you get strong. This build is high risk high reward and creates the Karthus stereotype where he only need to press R.
The rune page you will be using is the first rune page on this guide with Dark Harvest, This is big damage, the pop the enemy ADC in one Lay Waste rune. Aggressive plays and 1v1's are the name of the game with this rune page.

Playing lane


Starting with Doran's Ring you can immediately start bullying your lane opponent with Lay Waste assuming you took this build into a winning match up. Their CD's will often be much higher than yours enabling you to punish for any missed skill shots with Wall of Pain. This only get better as lane goes on as you get more mana And eventual they will not even be able to stay under tower from the barrage of Lay Waste's. The main thing to worry about is of course the jungler, as if you play aggressive as an immobile mage you are bound to get ganked. Depending on the enemy JG, if they don't have a good gap closer and with a good dodge or two of a skill shot a 2v1 is not hard. Just target the likely not full health Jungler as they approach with Lay Waste and you can easily finish them off by the time they get to you. Make sure to kite away between Lay Waste's as that is one of the most important skills on Karthus. This may be the big damage low brain power build but do not fall into the trap that is Flash inting. Many new Karthus players Flash in to "abuse" passive but proceed to miss everything and die. Over time you will start to see the correct time to Flash in. The most often time to do it is when the opponent is doing baron and you need to stop it. Play like an artillery mage for most of fights until the time is right to go in with Defile on. you are back line but still you should die before the ADC unless they are useless. most likely take Exhaust allowing easier 2v1 and better kill potential with the slow.

When to run this build


I said this before but run this into any wining match up or squishy enemy team. This build is also the best to start with as a new Karthus player. simple play style and still useful late even when behind. This build can also be altered to an extent to work decently in most cases.


[*] Scaling late game build

This build is the most simple to play as it revolves around playing safe and farming for late. The main two items being Rod of Ages and Archangel's Staff and getting them stacked. Of course Karthus stacks them fast but even so the power spike is still late. Of course you can go into any item after the first two as well, making it versatile. You can use almost any kind of rune page and can play how you want late game as long as you play safe early. This build makes killing potential in lane almost zero with first items being Tear of the Goddess and Catalyst of Aeons. With no mana problems you can farm forever you will and probably take Teleport for a better scaling experience. This build has the highest AP of all the builds for late game but the worst early even early-mid game out of any of them.
Both rune pages can work for this build, both provide Presence of Mind. The main difference being do you want more sustain and some late game burst of Dark Harvest rune page or the poke and scaling of the Summon Aery rune page. Honestly this is based on preference and what you are more comfortable with.

Playing lane


The most simple lane phase to play, farm and play back. The likelihood of you killing you opponent is very low and the champions that you play this build into you will not want to try to kill the opponent as it will not end well. Ad for starting items, it depends of what rune page you took, if you took Ravenous Hunter then Doran's Ring is the best option. If you did not take it then Corrupting Potion is most likely the pick. A jungle gank can help you get to late game faster as can a lucky Requiem so keep watch for them at all times. This build will out scale or allow you to scale with them so not dying in laneing phase is essential.

When to run this build


As I said before, this is for out scaling or scaling with the lane opponent namely the two big problems being Kassadin and Vladimir two very hard match ups but this build gives you a chance. other times that you can build this is when you don't have much kill potential on either side of the lane such as Ryze.

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