This guide has not yet been updated for the current season. Please keep this in mind while reading. You can see the most recently updated guides on the browse guides page
Karthus Build Guide by Hamstertamer
Your votes and comments encourage our guide authors to continue
creating helpful guides for the League of Legends community.
++8 ability haste
+9 Adaptive (5.4 AD or 9 AP)
+8 Magic Resist
Threats & Synergies
A good kha will counterjungle you hard to punish your pick, he beats you 1v1 but if you avoid him and counterjungle him when you know he's ganking elsewhere you can go even early game. You have amazing teamfight presence and he has none so just group with your team ASAP to win.
Jumps on you and oneshots you with very little counterplay, and will counterjungle you hard to abuse his 1v1 advantage. On top of this, his ultimate blocks both your Q and your ult. Later in the game can be kited with zhonyas/rylai. But IMO the worst jungle matchup.
You have no hard CC so you can't deal with him, his ult makes him immune to your slow, and he can block your ult with his W. He beats you 1v1, he'll counterjungle you and you can't contest. Just group with your team and hope they can CC him so you can land your Q. Get zhonyas so he can't focus you.
More a toplaner than a jungler, but that guy has massive magic resist and is really not fun to play against. Need early voidstaff + morello.
Not a jungler, but his massive magic resist is a pain to play against, plus he can purge your slow. Not fun, you have no way to deal with him unless massively fed. Need early voidstaff + rylai.
Not a jungler, but his ultimate gives him absurd magic resist so very hard to deal with, used to be my go-to ban when he was meta. Need early voidstaff + rylai.
I'm putting only the difficult matchups on this list so you know what to ban/avoid, everything else is not a problem.
Can snowball hard on you early game, but not a threat in a teamfight especially if you have zhonyas.
BS champ. Huge mobility, huge damage, huge magic resist, zero counterplay. Can also cancel your ult with Q. Permaban.
Her counterjungling/solokill potential on you is scary early game, but you make up for it with your far superior teamfight presence.
Beats you early, but get a zhonyas and he can't touch you for the rest of the game.
The only ADC that deals well with Karthus, can spellshield your ult. You can outplay it tho, focus her with Q in teamfights to force her to use her shield and then ult when it's down. Can be annoying but not worth a ban.
Can oneshot you from the other side of the map with only her Q+empowered W, which has zero counterplay. After this you're not in position with your passive to impact the fight. Just get MR and sit back. Thankfully you can often finish her off with ult when her passive procs.
Can oneshot you and steal your ult.
Her ult nullifies yours if she uses it before it hits, so she can take away kills from you...kinda. However your damage outscales her healing and she always sits at low HP because of her W so she'll often die to save teammates. Don't bother getting grievous wounds against her since she'll always heal before your spells hit, stack damage to oneshot her instead.
BS champ. Can oneshot you from 2 screens away so you're not in position to use your passive for damage. You need defensive items (zhonya/banshee). Use zhonyas just before her bubble puts you to sleep.
Champion Build Guide
While a midlane Karthus can be easily abused and quickly become free food for assassins or burst mages, a jungle Karthus is overall a much safer blind pick in any game and can just play reactively on the map in a bad jungle matchup, focusing on fast farm and ganks.
Have a nice read!
Transcendence + CDR stat shard + Archangel's Staff puts you close to 40% CDR very early in the game, which massively improves your clear speed by spamming Q as well as allow you to have your ult up all the time. The downside of many Karthus builds is that they sit at low amounts of CDR since AP tank items don't give any, so this is the best way to max out on it.
It may sound counter-intuitive to skip the jungle item Stalker's Blade - Runic Echoes but there's a reason for it. Runic echoes doesn't solve Karthus' mana problems since it doesn't give him a big enough mana pool to cover the massive cost of Defile in a fight, so with it you'll often run out of mana. Runic echoes doesn't give enough cooldown reduction either, while with the 20% CDR from archangel's plus the 20% CDR from your rune page, you'll reach 40% CDR very fast naturally. While archangel's is an expensive item, when you factor in the Fiendish Codex that you'd have to buy anyways if going for another build, it's actually a very cost-efficient buy.
The full magic penetration build will give you more damage than anything else you could buy. Always buy Oblivion Orb and later upgrade to morello for the magic penetration even when not facing healing, the way magic pen works is that it synergizes with itself since every source of it brings the enemy MR closer to zero, so the more you have the more effective it becomes. Even without any MR item or rune a melee champion sits at 53 MR, so you need the three penetration items to bring that to zero.
I don't build Rod of Ages because morello is just far more damage, try it out in practice tool if you don't believe me.
Maximizes your damage, especially on your ultimate.
Situational items to deal with assassins , but you already have 40% CDR with my build without one of those and Death Defied generally means you don't mind getting focused first in a fight so you can do without. The only cases where you absolutely need one of those is when facing champions that can oneshot you from long range like Zoe or LeBlanc, making your passive useless.
- Always go for a full clear (red->blue side->scuttle typically)
- Karthus is not bad at contesting scuttlecrabs early. Don't expect kills but Q+smite is solid for securing the crab and Q poke is good zoning. You're also very safe since you can just disengage with Wall of Pain.
- Don't counterjungle aggressively, but always do it reactively when you see the enemy jungler on the other side of the map.
- While he has decent ganking ability, Karthus is still at the core a farming jungler, and his biggest strength is his ability to flashfarm the entire map. Always clear empty lanes whenever you can.
- Time your ultimate right. Either you use it at the start of a fight so you can get assists, or at the end of a fight to pick off low health champions who are fleeing. But avoid using it in the middle of a fight since the enemy champions may die before you get the assist.
- When you die, you have time for 3 Lay Waste casts before your ultimate.