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Karthus Build Guide by CaptianMike

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League of Legends Build Guide Author CaptianMike

Embody death itself! (1k AP) (Mid and Top)

CaptianMike Last updated on January 29, 2018
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Team 1


Team 2

Cheat Sheet
Previous Champion Build Next Champion Build

Personal Build (Mid lane)

Karthus Build

LoL Path: Sorcery
LoL Rune: Arcane Comet
Arcane Comet
LoL Rune: Manaflow Band
Manaflow Band
LoL Rune: Transcendence
LoL Rune: Gathering Storm
Gathering Storm

LoL Path: Inspiration
LoL Rune: Magical Footwear
Magical Footwear
LoL Rune: Perfect Timing
Perfect Timing

+12 Attack Damage or +20 Ability Power, Adaptive

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Middle Lane
Ranked #13 in
Middle Lane
Win 51%
Get More Stats

Ability Sequence

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

Threats to Karthus with this build

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Threat Champion Notes
Cassiopeia Actually easy! You don't have any movement abilities so she can't hurt you with that, and your Q way out-damages hers. Watch out for her power spikes at level 2 and 6. Otherwise, look away after you use an ability. If you're constantly turning you head around, the odds that her ult will hit are low. Once you get ahead she is an easy kill to say the least.
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My name is Michael and I am a gold player on NA and my username is Main Got Nerfed. I love to play late game scaling/farming champions! My favorite class is duelist but for some reason when I played Karthus for the first time I fell in love! Literally all you have to do is farm and press R for kills to become the carry! Keep in mind I'm not a pro Karthus by any stretch of the imagination but I am pretty decent with him and this guide is to help you get there too. I'm going to keep this guide as up-to-date as possible.

Are you tired of enemies escaping with 1 hp? Are you tired of falling off late game and being useless? Do you like having the last laugh!? You've come to the right champion. Karthus is a champion unlike any other!

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Pros / Cons

    Very strong mid and late game!
    Strong team fighting!
    High damage output
    People always underestimate you
    Useful even after you die
    Still good even when behind
    Stacks tear insanely fast
Weak laning phase
Needs items to be useful
lacks hard cc
Mana hungry
Literally no escape besides flash

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Summoner Spells

After trying many combinations, flash and exhaust are my favorite. I've tried to run TP and it is good for the early game but in the mid to late game you lose out on dueling potential without exhaust. However for top lane I would recommend TP for overall map pressure. If your mid laner takes TP, then I would take exhaust because I love to duel. Ghost is ok, it can be viable some games but most of the time I would not recommend it. You need flash to avoid ganks and quickly reposition in fights. Ghost can be useless if they have a J4 on their team, or huge displacement ults like Gragas. 99% of the time if you get Rylai's it's just as good as Ghost.

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The Rod of Ages is a very strong item on Karthus as it gives him all the stats he needs: health, mana, and most importantly ability power. Build this item first in order to get the stacks as soon as possible. The next item that you should try and build is the Archangel' Staff. This will give you loads of mana plus a juicy 80 ap. The real reason behind it is for when it transforms into Seraph's Embrace. The shield lets you bait enemies into fighting you. It's very useful in team fights when a predictable burst will hit you (I.E. a lux ult, or a Darius ult) so you can soak most of it up. Personally my favorite item to get on a caster mage. Rabadon's Death cap is a self-explanatory item- pure power. Get this item 3rd if the enemy team is really squishy so you can kill carries as fast as possible. Otherwise, Rylai's is the next best option as the slow lets you hit your q much easier and once the enemy engages they won't leave. The perfect synergy with Rylai's is Liandry's Torment. Your E will dish out a solid amount of magic damage even to tanks due to the % current HP passive on Liandry's- Which is twice as effective due to Rylai's!

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New Runes

Our main tree will be the Sorcery Tree, since we use abilities as our primary source of damage. For the keystone, I take Arcane Comet over Summon Arie or Phase Rush. Arcane Comet has the best AP scaling, and we don't need the movement speed from Phase Rush. We also cannot utilize the second aspect of Summon Arie which is increasing shields given to allies. Mana Flow band is pretty explanatory- we are very mana hungry and need every bit of mana we can get. I personally choose Transcendence over Celerity. I focus on dealing the most damage overall. Celerity might work in conjunction with Phase Rush. Finally, I take gathering storm because it matches my playstyle- waiting until late game for maximum strength. Scorch is also a viable option.

The second tree I chose inspiration. There are plenty of options in this tree, so I would encourage you to pick ones that suit your style- that's what these runes are all about. I personally choose Magical Footwear and Perfect Timing. Future's market is another good option.

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Play Style

Early game

This is the laning phase and the most important thing here you need to remind yourself is that you are weak. You are nothing. Everyone out trades you, so you shouldn't get close enough to do it. The best you can do it try to poke them down. Only use your Q to last hit so you won't push. Do your best to make sure the minion is isolated, so you can deal double damage and ensure the last hit. Take into consideration of the slight delay in your Q or you might miss some CS. Once you hit 6 make sure to check on other lanes to see if you can ult for kills. Generally this is how you'll be getting all your kills early game. Your goal here is to CS as much as possible and die as little as you can.

Mid game
At this point there might be small skirmishes and roaming champions everywhere but you still have not reached your maximum strength. Depending on how fed you are, you might be able to 1v1 the enemy ADC assuming you can hit a couple Qs. Still, focus on going to any lane with big waves to get CS. You can go for some kills at this part of the game but more often than not, you really should just be playing safely still until late game where your true power shines.

Late Game
AKA you have 4-5 items.
You are a very powerful champion and better yet others have fallen off at this point. Your mission here is to dictate and win teamfights. You can use your W to catch an enemy out of position for an easy engage with the 70% slow it gives. Once they get in your E range, they will be dead. Know that a lot of your damage comes from you E so you want to be close enough in a fight to have your E ticking on enemies but far enough that you won't be assassinated.

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Team Fighting

Karthus is one of the best team fighting mages that exist. He has a high damage AOE ability (His E) and his wall reduces magic resistance by 15% of all who walk through it! Meaning your teammates benefits from this too.

If you find yourself setting up for a teamfight and both teams are in the poking phase before the fight begins, use your Q relentlessly as it has a low cost and cool down yet dishes out a lot of damage. Don't be afraid if you q and the target isn't alone for the double damage. Any damage is good damage. Now the team fight begins. Your role is to stand back and take out the highest priority target in your range with your E and Q. If your target dies, repeat with the next highest priority. If you know you will die soon in a fight walk straight into the enemy team. Yup, that's right. Run right into them and give them pain! Your E will constantly be doing 100s of damage and once you die you can safely cast your R without being afraid that CC will interrupt it. Do not be afraid of death. That is the difficult part of Karthus sometimes. Be real with yourself and if you know there is little hope of an escape, go in and die to deal as much damage as you can so your teammates can finish off the fight. This is so important that I would even flash into the enemy team to get their backline in the damage too. Remember, you are death.

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There is an actually good reason for having no CDR in my main Karthus build. Short answer: Your E does not scale with CDR.
In depth answer: You may want CDR for your ultimate, but in reality, there are very few times in a game where you can use your ultimate effectively. It is not uncommon to only use your ultimate once before the 30-minute mark. If you use your ultimate that seldom, it is clear that you don't need CDR to repeatedly use that ability. Also, your E becomes a huge source of damage in the late game but it is a toggled ability so it doesn't scale at all with CDR. Finally, if even after that you still want to grab an item with some CDR, your purchase won't be 100% cost efficient. You are paying for that CDR when you won't even need it so therefore, you should stay away from CDR items in most situations.

After doing many mathematical calculations, I discovered that building CDR is viable. The main reason for doing this is to get your Q cooldown lowered, so it can be spammed even faster. The results from my calculations are simple. If you can land your Qs, build CDR. If you aren't good at landing Qs, then this build which has more AP will be better. The exact cutoff is that if you can land 47% of your Qs or more, it's better to get CDR. Note that CDR builds have less AP overall so your ultimate won't be as strong as you may be used to. I recommend checking out Ding D-ng's guide for good CDR builds and playstyles.

TL;DR- If you're skilled, buy CDR.

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Tips & Tricks

-To charge tear of the goddess faster, have your E on while you recall and sit in base. Your E counts as a spell casted so it will passively charge while you recall/are sitting in base. However, this should not be used to stack tear outside of these situations; using your Q is a much better method

-You can convert mana to health at an affordable cost if you have at least the tear and Catalyst of Aeons. If you keep your E on it costs mana which is converted to health, and part of the mana spent is refunded. You heal up to 25 health per second!

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Top Lane

I would not first pick Karthus for top lane. He is easily countered by fighters with gap closers. I would only pick Karthus top if you know that you will be facing a tank (like Shen, or Malphite). Generally speaking, you pick top lane if you're looking for an uneventful farm lane which will make you stronger sooner in the game.

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