Jarvan IV vs Cho'Gath

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.

Keep moving against him: Rupture (Q) strikes an area on the ground, and an enemy standing still takes a knock-up, damage and a slow.

Punish him when he goes for last hits: Carnivore (passive) restores health and mana for each unit he kills, and he lasts a long time in lane if you let him farm.

If you have range, keep your distance: his kit has no dash, only the slows from Rupture (Q) and Vorpal Spikes (E).

Don't stay in melee range at low health when Feast (R) is up: its true damage ignores your resistances, even if you're a tank.