K'Sante vs Mordekaiser

Stack Ntofo Strikes (Q) on minions: after 2 hits, the next cast becomes a shockwave that stuns and pulls, so save it for the champion.

Charge Path Maker (W) when they throw CC at you: while charging, you're Unstoppable and take less damage, then your dash knocks back and stuns.

Cast Footwork (E) toward an ally to protect them or escape: the dash goes much farther, and you both gain a shield.

Knock your target into a wall with All Out (R): they go through it, you follow, and you hit harder at the cost of some of your health and resistances.

Stay near your minions against Obliterate (Q): its damage increases when it hits only one enemy.

Dodge Death's Grasp (E): it pulls you toward him, into his other spells, and it has a 16 to 8 second cooldown.

If you have range, kite him: Mordekaiser has no dash, and only Death's Grasp (E), which pulls you in, closes the distance.

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.