Garen vs Cho'Gath

Trade with Decisive Strike (Q), then Judgment (E), and back off: the Decisive Strike silence stops your opponent from answering with spells.

During Judgment (E), stay closer to your opponent than to their minions: the nearest enemy takes extra damage.

After a trade, back off until Perseverance (passive) kicks in: without recent damage taken, you regenerate part of your health every second.

Activate Courage (W) just before the bulk of the damage: you first gain a shield and tenacity, then a longer damage reduction.

Save Demacian Justice (R) to finish: its true damage grows with the target's missing health.

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.