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Karthus Build Guide by Aqua Dragon

Middle [14.4] Diamond Tank Karthus - Slow Death

Middle [14.4] Diamond Tank Karthus - Slow Death

Updated on February 28, 2024
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League of Legends Build Guide Author Aqua Dragon Build Guide By Aqua Dragon 126 17 1,368,150 Views 108 Comments
126 17 1,368,150 Views 108 Comments League of Legends Build Guide Author Aqua Dragon Karthus Build Guide By Aqua Dragon Updated on February 28, 2024
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Champion Build Guide

[14.4] Diamond Tank Karthus - Slow Death

By Aqua Dragon
The Author

Aquaired Skillset

Hi! Iā€™m Aqua Dragon. I've been in Diamond for multiple seasons and I play Tank Karthus.

I also play:

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Pros and Cons


  • Moves quickly; easily sticks to opponents
  • Incredible mana sustain during laning
  • Powerful initiator
  • Strong early kill potential
  • Great roam during laning phase


  • Weak waveclear
  • Devours mana rapidly during fights
  • No inherent tankiness
  • No inherent health sustain
  • Low AP; ultimate is weak

What is Tank Karthus?

Righteous Requiem

Karthus is most known for amassing massive AP, sacrificing themselves into the fray to do massive burst damage with Defile, and cleaning opponents with a half-health chunking Requiem. However, it turns out Karthus is able to viably become a more sustained-damage tank that trades off the chunking power of the ult to become a higher-ranged Singed during teamfights.

This is possible because Karthus only has a great AP ratio on Requiem. It is fairly lackluster on Lay Waste and Defile. The AP ratios of each spell are:

--Lay Waste (Single): 0.7
Lay Waste (Multiple): 0.35
--.--.---.-.-.--.-.-.-Defile: 0.2

Though the 0.7 scaling on Lay Waste is nice, it only applies when hitting a single target. This is largely only feasible during laning. In teamfights it's far more likely to only get multi-hit Lay Wastes unless Karthus is chasing someone down.

To be fair, both Defile and Lay Waste hit every second, making the low AP ratio more valuable. But also to be fair, the base damage is also hitting every second. In reality, it's less about the AP ratio, and more about the Scaling to Base ratio.

Getting AP is primarily useful for Requiem, not for the other spells. However Requiem is on an impressively long cooldown and there are an amazing number of ways to nullify its damage. Instead of banking most of the damage into Requiem, could power be transferred away into the rest of the kit? Tank Karthus answers this question with a resounding yes.

Glorious Defile

Tank Karthus does this by transforming into an Artillery Tank that abuses the base power of Defile. A standard AP Karthus tries to abuse the scaling on single-hit Lay Wastes to do damage, but this creates unreliability in the damage output. In addition, maxing Lay Waste first prevents the surprising power of Defile from being abused.

Each level of Defile is on par in damage with its equal-level Lay Waste counterpart. This is to say, a Level 3 multi-hit Lay Waste does non-guaranteed 79 damage. A Level 3 Defile does 70 largely-guaranteed damage in an AOE. Thus, maxing Defile first is like hitting your opponent with a non-amplified Lay Waste every second. This isn't strictly true and has nuance, but the principle is the point.

There's good reason Defile isn't used this way. Its high mana drain is, well, draining. In addition, putting yourself into range of its use is extremely dangerous for the fragile Karthus.

This is where Tank Karthus moves in (literally). Because Tank Karthus doesn't have to focus on AP items, they are able to focus more heavily on maximizing a mana pool and building survivability to make amazing use of Defile. Because of this, you will often end up doing damage comparable to a full AP Karthus. The damage will be more sustained by comparison and suffers the disadvantages of the damage style, but the presence in fights still demands respect.
Why Mid Instead of Top?

Middling Issues

Tank Karthus might be a tank, but they still have some disadvantages at top lane compared to melee tanks.

First, consistent pressure is much more mandatory at top, which pKarthus struggles with due to their lack of pushing power. Additionally, Tank Karthus is pretty reliant on mana to deal damage, which makes it difficult to kill tankier targets with Defile. Against squishy top laners like Teemo, this disadvantage is much less pronounced, and in fact such ranged matchups are heavily in Tank Karthus' favor.

Second, Tank Karthus enjoys roaming around on foot and setting up for teamfights, which are both more optimally geared for mid lane than the top lane. Fights are more likely to occur at dragon, and Mid offers two different lanes to roam to instead of just one.

Tank Karthus can still be functional at top lane, but I prefer it at mid to realize its full potential.

Karthinking About Runes

Arcane Comet and Summon Aery

Comet adds excellent damage by reducing cooldown 4 times per second per target. Aery is another excellent alternative that benefits from how close Tank Karthus gets in fights. Phase Rush gives up too much laning power.

Manaflow Band

Manaflow's extra spells keeps Karthus alive longer than Orb's pitiful shield.


Celerity because the other options suck for Tank Karthus.

Gathering Storm

The least bad option; it's too difficult to capitalize on Scorch's damage and roams with Waterwalking don't happen often enough.



Conditioning is why you're going Resolve. It's 12% more effective HP.


Overgrowth is a reliable pickup, giving more overall impact than the other more niche options.


Flat AP, Scaling Health, and Scaling Health

Adaptive Force because it's the least bad choice in the first row. Scaling health for maximum durability, though flat hp or tenacity are worthwile picks.

For a primary rune tree, Sorcery seems like an odd choice. Why not an option with more utility or tankiness?

There are some nice keystone choices in other pages whether it's Domination's Predator MS bonus for engages, Inspiration's Unsealed Spellbook for engage versatility, or even Resolve's Guardian for more tankiness during teamfights.

It all boils down to one thing:

Tank Karthus can't do their job if they can't compete in lane, and after ample testing, it was found that Comet / Aery are integral to competing.

This is really something that only experimentation can show. I've tried all the other options, fiddled with the build order tremendously, and generally tried as hard as I could to avoid just relying on raw damage. But in the end, Tank Karthus' laning phase is gimped too hard by anything other than Comet / Aery.

It's a shame then that Resolve becomes essentially mandatory as the secondary rune tree. The bonus MR and Armor are needed because Karthus has no inherent defensive bonuses.

This does mean you don't get access to any of the cooler runes that would otherwise synergize nicely, but that's just the sacrifice that has to be made when delicately balancing durability and damage.
Build Order

Soul Build Order

Tank Karthus' playstyle favors abusing Defile. Thus, there's a large preference on items that punish enemies for staying in Defile's radius.

Create Item Set

AP is not the goal of the build, making Tear preferable.
You won't be upgrading this Tear for a long time, if ever.




Magic Resist


Build items based on the most immediate threats.

Build Sorcs after a complete item. You can build Rylais if you feel quite tanky.

Don't upgrade into Archangels until you have literally no other choice.

Unrecommended Tank / Bruiser Items

I'd love to give any of these options a glowing recommendation since they're all a ton of fun to build. Sadly they all have some huge downside that ruins the delicate balance of durability and damage.

The perfect mix of tank and power needs to be stirred together. These options skew too much in the damage / utility / durability direction that Tank Karthus cannot do an effective job balancing the two foundations. Worse, some items have too much cost in their wasted Ability Haste, others in wasted mana, others in surprisingly-low raw DPS, and others because their effects are clunky or outright impossible to use.

In short, the answer to "Why don't you use x item from this list" is almost always "because I tested it extensively and it didn't work."
Stage of the Game

Deathsinger's Stage


In the early game, your goals are to
  • Farm waves from a distance
  • Dive opponents regularly with Defile and force summoner spells
  • Replenish mana between these attacks with Defile's mana regen

Bully Hard: Don't let up! Make the opponent suffer for every minion they wish to get.

Abuse Defile's Mana Refund: Each dive is heavily mana intensive. Early levels in Defile will provide a quick way to get more mana as you prepare for the next tackle.

Farm with Autos: Using Lay Waste to farm will not return nearly as much net mana as farming with autos, so avoid relying on it when you can.

Abuse Aery / Comet: Time your Lay Waste harass with Aery / Comet to maximize the poke damage. It adds up exceedingly fast.

Roam Often: You can start roaming very early on due how abusrdly fast Tank Karthus can clear the wave. You even can just walk into the middle of a wave, clear it, recall, and return to lane in time for the next wave.

Don't Overly Rely on Lay Waste: It's sometimes better not to use Lay Waste during defile tackles, as the mana cost expends a second of Defile's time. Unless you know for sure that you'll land the hit, let Defile do the brunt of the work.

Autoattack During Tackles: At early levels, the autos will nearly as much damage as Lay Waste!

Don't Level Up Wall of Pain Until 7: It has an exorbitant mana cost and the slow it provides isn't as strong as simply getting earlier points in Lay Waste and Defile.

Learn to Efficiently Clear Waves: Let Defile and Bamis hit the tankiest minion(s) first, though all of them if possible. Then, use Lay Waste on the tankiest minion(s) first. Ideally, the entire minion wave dies at the same time, maximizing overall clearing speed.


As the laning phase ends, you will start taking on a more aggressive role.
  • Initiate fights with Wall of Pain.
  • Pick a target in the fight and stick to them
  • Chase down lonely opponents and kill them
  • Use Requiem to clean up easy kills

Dive Headlong: You are the one who decides when fights happen due to the enormously powerful initiation. Lead the charge; you decide when it's time.

Disengage, then Ult: Opponents who barely escape from your defile tackles can be shot down with Requiem. Take note however that Tank Karthus' Requiem is not too strong. Keep tabs on its base damage and use that number to figure out when it's time to ult.

Preemptively Ult Often: It is often better to just use Requiem preemptively instead of trying to execute targets with it. Notice a fight happening in another lane? Just ult anyway. Otherwise, trying to execute targets will usually just leave Requiem on cooldown for half the game.

Duel Regularly: Your dueling power is fairly respectable. If you see someone extending too far to push or too far in your jungle, use your superior mobility with Exhaust to defile them down.

Use Full Defile Range on Melee Champs: You move pretty fast and are tanky, but that's no reason to take free hits. Try to skirt melee enemies at the edge of your defile instead of always standing right next to them.

Get Close to Ranged Champs for Aery Procs: Try to stay especially close to ranged targets when using Defile since this will allow Aery to refresh multiple times over the course of a fight. The closer you are, the faster it refreshes.

Watch Your Mana: Once you're out of mana, you're spent. You have no real mana regeneration outside of lane. Be cautious of your mana bar to make sure you won't overexert yourself before battles are truly done.


You retain a similarly sticky role as the game reaches its conclusion
  • Build defensive items for the situation
  • Make picks on lonely opponents with your mobility
  • Try to attract the attention of as many opponents as possible in fights

Lead Fights: Continue to start fights when you see openings. You remain the dictator of when fights begin.

Consider Thornmail: Thornmail is especially powerful on Karthus. It's easy to get into close range of ADC's. Once Thornmail nullifies their lifesteal, their death becomes guaranteed, especially with an Exhaust. If you can force the ADC away by yourself, you can gain an immense fighting advantage for your team.

Spam Lay Waste: Your Lay Waste will start packing a bit of a hit now. Feel free to spam it for offense, though be mindful of your mana.
This guide was a lot of fun to write, and I hope you all have learned everything you would have liked.

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League of Legends Build Guide Author Aqua Dragon
Aqua Dragon Karthus Guide
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[14.4] Diamond Tank Karthus - Slow Death

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