Matchup

Heavy AP damageCountered by stasisSustained DPSHigh burst

You are stronger early — look to snowball before your opponent scales.

Build vs Karthus

Build adapted to this matchup

Starting items

Doran's Ring
Health Potion
x2

Core build

Hextech Gunblade
1Mage
Shadowflame
2vs Tank
Mejai's Soulstealer
3

Standard

Sorcerer's Shoes
4Magic pen
Zhonya's Hourglass
5vs AD

Summoner spells

41486%
12149%

Anti AD

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

Anti AP

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

Anti Tank

Void Staff
5vs Tank

DPS

Rabadon's Deathcap
Mage
Lich Bane
Mage
100.0% WR1 games
DominationDomination
ElectrocuteElectrocute
Sudden ImpactSudden Impact
Grisly MementosGrisly Mementos
Ultimate HunterUltimate Hunter
ResolveResolve
Second WindSecond Wind
OvergrowthOvergrowth
Adaptive ForceAdaptive ForceHealth Scaling

Power Spikes

Strength by game phase

Early (0-15)
Mid (15-30)
Late (30+)
AkaliAkali
KarthusKarthus
Aggressive
Careful
Careful

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