Mordekaiser vs Yorick

Aim Obliterate (Q) at a lone enemy: if only one enemy is hit, the damage increases.

Hit champions or monsters three times, then stay close: Darkness Rise (passive) then surrounds you with a damage aura and gives you move speed.

Pull your targets into the Obliterate (Q) zone with Death's Grasp (E): each spell that hits also counts toward Darkness Rise (passive).

Cast Indestructible (W) when you're taking damage: it turns stored damage into a shield, and a recast converts part of it into health.

Cast Realm of Death (R) on their carry, or their jungler near an objective: you isolate them with you, steal part of their stats, and keep them if you kill them.

Dodge Mourning Mist (E): once marked, you lose armor, his nearby graves keep raising Mist Walkers, and his units rush toward you.

Kill his Mist Walkers, summoned by Shepherd of Souls (passive), before going for him: a single auto or single-target spell is enough for each.

If Dark Procession (W) traps you, hit the wall to break it instead of waiting for it to disappear.

If you can, take down the Maiden of the Mist before Yorick: summoned by Eulogy of the Isles (R), she carries a large part of his damage and push.

Don't let him split push alone: with the Eulogy of the Isles (R) Maiden and his Mist Walkers, he quickly threatens a tower. Send someone to answer him.