Karthus Guide

Key Insights
If
Karthus
Q
only hits one enemy, it deals double damage.
Karthus
Q
and
Karthus
W
reveal their affected areas.
Karthus
E
deals an extra tick of damage when Karthus recasts it.
Karthus
R
damages all targetable enemy champions.
Strengths
Even if Karthus is killed first, he continues fighting with
Karthus
P
, giving his team an advantage in fights since enemy resources were used on him.
Forces enemies to play with a "lower HP bar" since he can cast
Karthus
R
at any point to finish them off.
Synergizes well with
Liandry's Torment
,
Shadowflame
,
Horizon Focus
,
Rabadon's Deathcap
,
Zhonya's Hourglass
, and
Rylai's Crystal Scepter
. Can opt for
Night Harvester
or
Luden's Companion
for more burst.
Weaknesses
Completely immobile, leaving him vulnerable to ganks.
When fighting, if Karthus misses a single
Karthus
Q
, it becomes much harder to land one.
Buying
Edge of Night
/
Hexdrinker
as an AD champion,
Banshee's Veil
as a mage, or
Locket of the Iron Solari
as a support/tank will aid in negating
Karthus
R
's damage.