Jarvan IV vs Naafiri

Plant Demacian Standard (E), then cast Dragon Strike (Q) toward it: you fly to the flag and knock enemies in your path into the air.

Land an auto as soon as you reach your target: Martial Cadence (passive) adds damage based on their current health, then only triggers on them again after a few seconds.

Cast Cataclysm (R) on a carry who is away from their team: the arena is impassable, and you can recast to collapse it if it gets in your allies' way.

In teamfights, plant Demacian Standard (E) near the allies who are attacking: it gives them attack speed while they stay close to it.

Dodge Darkin Daggers (Q): her pack leaps onto the first champion hit, and the second dagger hits harder if you're already bleeding.

If you have AoE spells, hit her pack too: each packmate killed lowers her damage. Do it before Eviscerate (E) calls them back and heals them.

Save your targeted spells for after The Call of the Pack (W): for a brief moment, she and her pack are untargetable.

Avoid crossing the map alone against her: Hounds' Pursuit (R) lets her dash onto a champion from range, and a takedown lets her recast it.