What started as an off-meta bot lane pick has now become one of the best carries the role has ever produced. APC Karthus is often described as the pinnacle of AP bot lane champions and he definitely deserves that title.

But in order for Karthus to create and snowball early leads so that he can carry in the late game, he needs the right support partner.

Broadly speaking, Karthus needs a support that can slow his enemies down so that he can aim his Q. Additionally, any support that can speed up Karthus or CC the enemy team so that he can get in range is also a good pick in general.

Luckily for us, there are plenty of such candidates in League of Legends. And here I’ll give you the 6 champions I’ve had the most success with when it comes to supporting Karthus.

6. Ashe


Ashe also started as an off-meta support in LoL but she’s now one of the best picks for the role. Her unmatched ability to keep enemy champions slowed offers a great level of utility, especially for Karthus.

Ashe and Karthus can play a very aggressive laning phase. With the poke from Ashe’s W, the duo can zone their opponents and constantly threaten them.

After level 3, Karthus and Ashe can constantly pressure the enemy laners with ranged spells. Ashe’s slow allows Karthus to aim his Qs much better and isolate targets so that the damage is doubled.

The great thing about this duo is that their damage is mixed. Ashe deals physical damage and Karthus magic damage. And because their opponents can’t prioritize armor over magic resist and vice versa, their laning phase is really difficult.

After level 6, Karthus and Ashe can start impacting the map. Both champions have global ultimates which simply means that they can start and finish fights even in the top lane.

With Ashe’s stun and Karthus’ high damaging ultimate, the duo scales incredibly well in the late game. The setup is easy to execute and all they need to do is apply slow and have Karthus run the entire enemy team with his presence. 

If you’re an Ashe enjoyer, here are the best ADC partners for Ashe support.

Recommended Items for Ashe

Imperial Mandate item

One item that I really like in this situation is Imperial Mandate on Ashe. It marks enemy champions and makes them receive more damage from Karthus after Ashe slows or stuns them. So, definitely buy that one.

Ashe can also go for Chempunk Chainsword and apply Grevious Wounds to make Karthus’ job of killing enemies much easier. The item will help you lower the overall healing from your opponents. 

But it also grants lots of ability haste which is definitely useful for Ashe. 

5. Maokai


Maokai is another off-meta support I regularly play with Karthus bot lane. He’s got a fantastic toolkit that allows Karthus to carry with ease.

Early on, Maokai’s job is to throw as many saplings into the bot lane bushes as possible. Stacking them there means that the enemy laners can’t use them to sneak-poke Karthus or threaten him in any way from that angle. 

On the other hand, Maokai’s saplings deal a lot of damage early on, applying slow in a small radius when they detonate. They can be a great opening for Maokai to use his W and set up the fight for Karthus.

Maokai’s root is a great way to enable Karthus to deal extra damage. Since it’s a single-target, point-click ability, Maokai can instantly catch the enemy ADC and have Karthus cast two or three Qs on an isolated target.

Additionally, Maokai can push the snared enemy with his Q so into Karthus is in range of his E.

In the mid and late game, Maokai and Karthus have a great engage thanks to Maokai’s R. Nature’s Grasp can create the perfect opportunity for Karthus to go in between the enemy team, apply as much damage as possible (even die) and win the teamfight alone.

Both champions deals magic damage and they’re an excellent pair into all-AD team comp.

Recommended Items for Maokai

Evenshroud item

Some items that can help Maokai do a better job here are Evenshroud and Imperial Mandate.

With Evenshroud, Maokai can make all nearby enemy champions take increased damage when he immobilizes one of them. And Imperial Mandate does a similar job but it requires an ally to damage the target after the CC in order to trigger the bonus damage.

Read Also: 7 Best Synergy ADCs to Play with Maokai Support

4. Seraphine


For many players, Seraphine is one of the most broken support champions, no matter with whom she’s partnered up.

But when it comes to Karthus, she’s really one of the best champions you can possibly pick. She’s got enough damage, lots crowd control, and even a shield/heal to protect Karthus during the early game.

What I love about Seraphine and Karthus is their ability to control the bot side of the map like no one else. Since level 1, they can apply pressure thanks to their long-range abilities and keep the waves pushed.

What this does is that it allows their jungler to path bot side and take all objectives, even invade the enemy jungle. With their utility, Karthus and Seraphine can support any aggressive jungler by constantly slowing enemies, dealing AoE damage, and casting sheilds/heals.

When it comes to team fights, Seraphine’s R is one of the best AoE CC spells in the entire League of Legends. If it catches more than two enemy champions, Karthus can simply walk in and blast everyone with E and Q.

Additionally, the damage on Seraphine’s Q is increased the less HP her target has. This helps Karthus collect more Dark Harvest stacks overall and scale much faster.

When Karthus isn’t ready to die and trigger his passive, Seraphine’s W can extend his life even in the most critical situations.

And if you’re interested here are Seraphine’s best ADC partners for the bot lane.

Recommended Items for Seraphine

Rylai's Crystal Scepter item

There are two key items to buy on Seraphine whenever she’s together with Karthus in the bot lane.

First, Rylai’s Crystal Scepter is simply a must because the item applies slow effect with every ability used, even Seraphine’s Q. But its real value here is in the fact that it allows Seraphine to stun and not only root her targets when she double-casts her E.

And it helps Karthus with aiming his Q overall.

Second, Moonstone Renewer improves Seraphine’s W and applies constant heal whenever she is in combat. This can help Karthus stay alive during the mid and late game fights.

Read Also: 5 Best Supports for Seraphine APC

3. Nami


Nami is an exceptional support champion for all AP bot laners, including Karthus. She can buff up spellcasters to deal more damage which is definitely what you want here as well.

Nami’s and Karthus’ power is best seen in 2v2 fights. With her E, Tidecaller’s Blessing, Nami grants a buff to Karthus that makes his next 3 spells (or basic attacks) to deal bonus magic damage while also applying slow effect on the target.

The best way to utilize this effect is to use all 3 charges on Karthus’ Q, preferably on a single target. The amount of damage that each Karthus’ Q can do in combination with Nami’s E is honestly broken, even on level 1.

But besides this, each time Nami uses her E on Karthus, she also grants him bonus movement speed which is definitely useful on an immobile champion. The same can be said for her W which heals allies and damages enemies.

Additionally, both of Nami’s Q and R are AoE knock-ups that give Karthus more than enough time to spread his damage around. For example, when Nami hits a bubble on the enemy carry, Karthus can quickly cast two or three Qs on them.

This duo is especially powerful later on when Nami can empower Karthus’ ultimate to deal even more damage than it’s supposed to.

Recommended Items for Nami

Staff of Flowing Water item

Here there are also two important items I must recommend for Nami. These are Chemtech Putrifier and Staff of Flowing Water.

Chemtech Putrifier is your preferred item against healing in League of Legends. It works by having your carry (Karthus in this situation) dealing damage while affected by one of Nami’s spells.

But the essential item is Staff of Flowing Water because when you do cast Nami’s E or W on Karthus, the item grants bonus ability power and ability haste for several seconds. So, it’s really powerful here!

2. Swain

Swain isn’t the most popular support in League of Legends. However, his playstyle and ability kit are almost ideal for supporting Karthus and allowing him to carry.

For starters, the best reason to play Swain support for Karthus is his dominating presence in the bot lane. Even on level 1, Swain’s threat thanks to his E is huge. No one likes to be pulled into a barrage of Karthus’ Qs, so enemies are automatically forced to play passively.

Swain offers both damage and crowd control. As a mage, this champion usually builds offensively and ends up as a second AP carry from the bot lane. But the great thing about Swain is that he scales extremely well too, maybe even better than Karthus.

In the 2v2 bot lan skirmishes, Swain can always be the frontline, pulling enemies, slowing them, and applying AoE damage. This frees Karthus to back him up without having to worry about everyone collapsing on him.

Once Swain gets to level 6 and unlocks his ultimate, he becomes a team fight monster. With his R, he can control the battlefield and slow everyone down (especially with Ryalai’s Crystal Scepter) so that Karthus can decimate them from behind.

Playing Karthus with Swain usually requires a lot more aggression than regularly. You may not want to duel everyone early on. But as soon as you get your core items you can definitely take over the entire map.

If instead you play Swain as an APC, here are his best supports.

Recommended Items for Swain

Morellonomicon item

Since both champions have a similar build, there aren’t too many unique items for either Swain or Karthus.

However, the one item that’s always a must-have is Morellonomicon. It’s the best AP item for combating healing in League of Legends because it significantly reduces it as you deal damage. So, get that one!

Read Also: 7 Best Synergy ADCs for Annie Support

1. Zilean


And the overall best-performing support for Karthus is Zilean. This champion is simply obnoxious in combination with Karthus and annoys everyone on the enemy team.

First of all, Zilean offers a lot of poke damage. His bombs stick to enemy champions and force them away from each other. In certain scenarios, this can even increase Karthus’ damage from his Qs because his opponents are likely to stand alone rather than stick together.

Moreover, Zilean’s bombs can stun multiple champions. It’s not the easiest CC to hit but it definitely opens the opportunity for Karthus to annihilate the enemy team. Zilean can even slow targets with his E which makes Karthus’ job a lot easier.

On the other hand, Zilean has the best supportive ultimate in the entire League of Legends. It can revive Karthus and allow him to continue fighting even after being slain. And in combination with Karthus’ passive (which is a similar effect), it’s really annoying to play against.

If the slow, stun, damage, and reverse-death effect aren’t enough, Zilean can also grant lots of bonus movement speed to Karthus. This is very useful against a high-mobility team since Karthus has no other way to kite enemies.

In the late game, Zilean’s job is to fish for double bombs on the enemy team and keep an eye out for Karthus in team fights. His ultimate can always be saved for Karthus, especially if the early game has gone well.

Read Also: 7 Best Synergy ADCs for Zilean

Recommended Items for Zilean

Luden's Tempest item

When you play Zilean with Karthus, I’d strongly recommend going for a heavy-AP build.

Here, Luden’s Tempest can give you a huge burst of damage and set up the stage for Karthus. It grants all the stats you need on Zilean, so it’s the perfect item for an aggressive playstyle.


Despite not being the best meta carry in the bot lane, many people find lots of success with Karthus APC. With the right support, this champion can 1v9 games and destroy solo queue careers.

Because of this, make sure to pick one of the support champions you see on this list and give your Karthus the best chances for carrying. 

Good luck!

Read Also: 5 Best Supports for Yasuo ADC

Categorized in:

Bot Synergy, League of Legends,

Last Update: March 2, 2024