Welcome to my Karthus guide! Karthus is one of my favorite champions to play in the League, and I noticed there wasn't an in-depth guide on how to use his Lay Waste with his Defile to last hit as well as keep his mana up. So, I decided to write one!

As a caster, Karthus is much squishier than I think a close range hero like him needs to be - his Defile has a small range, and half his damage comes from it. This is where my choice in items come from (which I'll go into later), as well as my masteries.

Pros:

Karthus is an AMAZING farmer.
Surprisingly strong lane staying power.
Amazing harassment for almost no cost.
Can zone very easily past level 5-6.
Hard to gank, contrary to popular belief.

Cons:

Requires his amazing farm to do well in the later stages of the game.
Can be zoned at the start and lose effectiveness before hitting getting his stride.
Bad early game, on par with Vladimir.

I've experimented with having MP5 runes instead of CDRs. I decided to go CDR blues and yellows because he does need some CDR - like Vlad's Q, he receives massive benefits to his damage output from it - and he needs almost no mana regen except at the VERY start. MPen reds/quints are obvious, though I would hazard to say you could even replace those with CDRs if you were willing to sacrifice the small damage drop early game.

My masteries were something I had puzzled over quite a bit while I was learning to play him. Karthus needs a bit of help early game in tankiness, as well as quite a bit throughout the game. I went 9/21/0 as it still gives me the CDR from the offensive tree, as well as the spell penetration. My 21 in the defensive tree lets me start with a reasonable amount of health, armor, and magic resistance. This allows him to be more aggressive in the early game, as well as not removing from his damage too much.

I experimented with 21/0/9 and 21/9/0, but it was always too squishy to make it worth it. If you're playing lower level normals, I would probably go 21/9/0 instead, but in higher level normal games (summoner 25+), I think he needs to be less squishy to compete in a lane.

After playing games using Clarity, Ghost, Flash, Teleport, and a multitude of other summoner spells I thought might work, I decided Teleport and Flash were the best two to go with.

Karthus has a weak early game due to his lack of super-spammable spells before getting his tear and his defile. I played a few games playing Clarity, attempting to remedy this. I decided it wasn't an effective choice, as it became a useless spell with his 3,000 mana and ridiculous regeneration in the late ends of the game. A decent spell, at most.

I also tried Ghost, but decided his slow made it virtually useless except in certain situations. Again, a decent spell at most.

Flash is an amazing spell on almost any hero, so I decided to try it. It allows you to escape almost any gank if you're in a good position, when used in conjunction with your slow.

Teleport is also a good spell, though I find it especially effective on Karthus. It allows him to go back at minute 4 and return without losing more than 2-3 creeps, giving him a fast Tear and thus great laning/farming power. As well as this, it allows him to move quickly around the map when he needs to, aiding his teammates more quickly than if he had to run there.

I've found Teleport/Flash to be one of the best combinations to play on Karthus - at least, with my playstyle. It allows him to escape almost anything and gives him a way to get to his teammates quickly, as well as shop without loosing out on much, if anything.

Teleport/Flash, good spells.

Many people look at Karthus as a glass cannon run in there and KILL hero, or a hero that just presses R and kills you. I've experimented with many builds and, while it requires a lot of farm, this seems to be the best.

I originally went flat AP, without building any health into it. I found I died too quickly. So I hit upon this build. It gives him a good amount of health compared to most casters, which he needs due to his low range. It also allows him to keep enemies near his teammates longer, stay in fights longer, and thus do more damage.

You start with mana crystal and two health potions, to start building your tear of the goddess as soon as possible. When you have enough gold for your tear, use as much mana as you can to harass the enemy before teleporting to your base and buying it. Teleport back to your lane and continue farming/harassing.

You generally want to be finishing your Rod of Ages by the 17 minute mark, but any time before the 22-23 minute mark is fine.

I build Sorcerer's boots for obvious reasons.

I've been asked why I get my Rabadons before finishing my Archangels. I do this because, in my personal experience, getting the items for Rabadons gives you more AP than buying Archangels this early in the game. I also prefer to have the 30% bonus before buying my AA, as it gives a huge AP boost. I generally have 2k-2.5k mana around when I buy my AA, and I spike from 300 to 550 AP from that one item. Ultimately, it's your choice.

I like Rylai's Scepter because you have a slow, but it only lasts for a couple seconds. A permanent 15% slow is very strong with your lay waste - it gives you a much easier time landing Lay Waste, and lets your teammates keep up much more easily.

Zhonya's Hourglass is a great item for Karthus because of his Defile. I especially like it when I have some sort of spell vamp, as it allows me to heal for a few seconds. It's not much, but 400-500 health is quite a bit. As well as this, it allows Karthus to deal a lot of damage without taking any. Along with his passive, he becomes a very scary hero, with almost 10 seconds of extra damage.

In my items list, I listed Will of the Ancients. I do like getting this for the spell vamp - but only if you have a very strong farming game. You'd want to get the hextech revolver between your boots and finishing the Rod of Ages. I generally aim for this item if I know my enemy in lane has strong harass and I won't be able to counter it - it gives me amazing staying power because of my massive AoE magic damage.

Lay Waste is the bread and butter damage skill on Karthus. Using it properly is the difference between killing someone and them getting away with 4 hp. Understanding the AoE and the delay on it are the biggest parts of playing him. There is an 0.5 second delay before it deals damage, which means you have to know how to lead your enemy. There are two ways to do this.

You can learn to estimate the movement speeds (which you'll do over time, anyway), or use your slow. If you're just starting to learn Karthus, it's probably a better idea to learn to use your Q with your slow first, so I'll start with that.

Lay Waste has what I would call (as an avid Warcraft 3 player) about a 75 AoE. I don't know what the exact number in League of Legends is (as it's obviously on much smaller scale than W3), but learning the AoE gives you a very strong advantage over, say, another Karthus, who just spams his lay waste on top of the enemy - it allows you to ensure a hit, as well as nearly always ensure you get an easy lead with single target bombs. While spamming your Lay Waste on top of the enemy is a good way to get fast damage output, in the long run precision Lay Wastes that hit one enemy can be more crippling, as they take out the people who need to die more quickly.

Using your Wall of Pain to land easy Lay Wastes:

When Kayle runs through the ***, she receives a massive slow, so it becomes much easier to land your Lay Waste spell. When you know for sure that she is going to run in a direction (indicated by my arrow) you place a LW slightly in front of her. This leaves her to options: Run backwards, possibly into your slow again, staying inside your Defile for longer, or run into it.

A second example:

Leading an opponent without your Wall of Pain is almost exactly the same. The only difference is that they move faster, so you have to place it further ahead. This skill takes a lot of practice to hit well, so don't expect get it perfect your first time playing Karthus. Practice makes perfect!

Last hitting with Lay Waste is essential, as Karthus's 45 base attack damage makes it much harder to last hit than many other champions. Thankfully, this is much easier to do than hitting a Lay Waste of a moving enemy.

In this picture, I see the minion is being hit by only one of my minions, and so put a Lay Waste beside it. Think of Lay Waste as an autoattack that does twice the damage if you hit only one unit - roughly 80-85 at level 1. It takes half a second to do damage, and does about the same amount as a strong ranged AD hero.

Much of using this skill is something you learn gradually, and learn to do almost instinctively if you play Karthus enough. Don't be afraid to spam the spell if you know you can hit at least one person with it - it's got a short cooldown and virtually no mana cost!

At the start of the game, you want to focus more on farming than harassing - though if you can get free harassment in, you should always do it.

Requiem is, I think, the main attraction to people wanting to play Karthus. It's a very strong skill - a map wide nuke that hits every enemy hero, with a rather large delay. From level 6 onward you can pretty much guarantee a kill, assuming your teammates are fighting a fair fight.

It's not only used to score kills, though. Many times you'll want to use it in the middle of a fight and take the assists, rather than try for the kills - a nuke the enemy wasn't expecting from a person across the map is very strong, especially when it's a fair fight (2v2 or 3v3, etc).

Taking an average of 30% magic damage reduction at level 6, and completely disregarding shields, resistance buffs, or anything like that, a level one requiem will do about 175 damage. If you're mid lane, that's a good eighth of any side lane heroes health.

For your skill sequence, you want to be using your Q whenever you possibly can. If you have a clear shot at the enemy, you want to use it. If you're chasing after someone, you want to use your Wall of Pain in front of them, and then hit them with Lay Waste, keeping up with them so Defile can do damage too.

Karthus doesn't really have a defining skill sequence: Just use your Wall of Pain whenever it will slow the enemy, whether chasing and running. Always have your Defile on if you're fighting someone and they're close to you. Lay Waste, everywhere. If you can hit one of them, do it! The extra damage is great, because it barely costs you anything.

Early game, between 6 and 11, if you can land your Lay Wastes, Karthus does a lot more damage than people realize. If the enemy doesn't move, you get easy shots. If they do, they do less damage. It's a win/win situation.

Well, thank you for reading my guide, Summoners! I hope you enjoy your time playing Karthus, and I hope you learned something from my guide :).

And remember, Lay Waste!