Naafiri vs Cho'Gath

Recast Darkin Daggers (Q) on a target that's already bleeding: the second dagger deals the rest of the bleed plus damage based on their missing health, and heals you.

When your pack has taken hits, cast Eviscerate (E): your packmates come back to you at full health.

Cast The Call of the Pack (W) just before you engage: you're briefly untargetable, your pack grows, and you gain AD and move speed.

Push your wave, then roam toward an isolated champion: with Hounds' Pursuit (R), you and your pack dash onto them, and a takedown lets you recast 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.