Mordekaiser vs Warwick

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.

Keep your health above 50%: below that, Blood Hunt (W) gives him speed toward you and attack speed, three times more below 25%.

When he drops below 50% health, finish him fast, with CC if you have any: Eternal Hunger (passive) then heals him with each auto, three times more below 25%.

If you have a dash, don't count on it to escape his held bite: Jaws of the Beast (Q) makes him follow all your movement, then leap behind you.

In teamfights, stay behind your tankiest allies: Infinite Duress (R) suppresses the first champion hit, and its range grows with his move speed.

If you have Grievous Wounds, apply it to him: his autos heal him at low health, and Infinite Duress (R) heals him for all the damage it deals.