Matchup

Heavy AP damageCountered by stasisSustained DPSHigh burst

Build vs Karthus

Build adapted to this matchup

Starting items

Doran's Ring
Health Potion
x2

Core build

Dark Seal
1
Malignance
2Mage
Horizon Focus
3Mage

Standard

Sorcerer's Shoes
4Magic pen
Luden's Echo
5Mage

Summoner spells

42146%
41238%

Anti AD

Plated Steelcaps
4vs AD
Zhonya's Hourglass
5vs AD

Anti Heal

Morellonomicon
6vs Heal

Anti AP

Mercury's Treads
4vs CC
Banshee's Veil
5vs AP

Anti Tank

Shadowflame
5vs Tank
Stormsurge
vs Tank

DPS

Luden's Echo
Mage
Blackfire Torch
Mage
Rabadon's Deathcap
Mage
Liandry's Torment
Mage tank
100.0% WR1 games
SorcerySorcery
Arcane CometArcane Comet
Manaflow BandManaflow Band
TranscendenceTranscendence
ScorchScorch
PrecisionPrecision
Cut DownCut Down
Legend: HasteLegend: Haste
Adaptive ForceAdaptive ForceHealth Scaling

Power Spikes

Strength by game phase

Early (0-15)
Mid (15-30)
Late (30+)
VelkozVelkoz
KarthusKarthus
Neutral
Neutral
Neutral

Karthus's abilities

Passive, spells and ultimate

Death Defied (P)

Upon dying, Karthus enters a spirit form that allows him to continue casting spells.

Cooldowns

Cooldowns by spell rank

LevelQWER
30s15s0.5s
60s15s0.5s3m20
90s15s0.5s3m20
110s15s0.5s3m
160s15s0.5s2m40
180s15s0.5s2m40

Playing against Karthus

How to counter and exploit weaknesses

1

Zhonya's, Edge of Night, and Banshee's block/cancel his R — buy one of these items if Karthus focuses you.

2

His Q deals double damage on isolated targets: stay in your minions or near allies to split the damage.

3

Shields, Soraka R, and heals can counter his R if well-timed — save an emergency heal for Requiem.

4

Karthus is immobile and squishy — dive him quickly to eliminate him before he deals continuous damage.

Source: op.gg + LTL Engine · Patch 16.9.1 · May 9, 2026