Kayn vs Mordekaiser

Not enough games

Heavy AP damageSustained DPSHigh burstCountered by stasis

Build vs Mordekaiser

Build adapted to this matchup

Starting items

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Core build

1—

2—

3—

Standard

4vs Slow

5—

Summoner spells

96%

Other options

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62.5% WR8 games

Precision

Conqueror

Triumph

Legend: Haste

Last Stand

Sorcery

Transcendence

Axiom Arcanist

Strength by game phase

Passive, spells and ultimate

Darkness Rise (P)

Mordekaiser gains a powerful damage aura and Move Speed after landing 3 attacks or spells against champions or monsters.

Cooldowns by spell rank

Level	Q	W	E	R
3	8s	12s	16s	–
6	6s	12s	16s	2m
9	4s	11s	16s	2m
11	4s	10s	16s	1m50
16	4s	8s	12s	1m40
18	4s	8s	8s	1m40

Tips to maximize your impact

Pick your form based on their team
Take Rhaast against a tanky team, Shadow Assassin against squishy targets: The Darkin Scythe (passive) gives one healing, the other bonus damage at the start of fights.
Gank through walls
Gank through walls with Shadow Step (E): you move through terrain faster, and you heal when you first enter it.
Hide inside an enemy
To dodge a burst, cast Umbral Trespass (R) on a champion you just hit: inside, you're untargetable while your spells come back up.
As Rhaast, hit everyone
As Rhaast, hit as many champions as you can with your spells: The Darkin Scythe (passive) heals you for part of the ability damage they take.

How to counter and exploit weaknesses

Stay near your minions
Stay near your minions against Obliterate (Q): its damage increases when it hits only one enemy.
Dodge his Death's Grasp
Dodge Death's Grasp (E): it pulls you toward him, into his other spells, and it has a 16 to 8 second cooldown.
At range, kite him
If you have range, kite him: Mordekaiser has no dash, and only Death's Grasp (E), which pulls you in, closes the distance.
Save your mobility in his R
In Realm of Death (R), save your mobility spells to escape him rather than for the duel: he steals part of your stats, and keeps them if he kills you.

Patch 16.21.1