Trundle vs Cho'Gath

Start your trades with Chomp (Q): the empowered auto slows your target, then steals some of their attack damage, which matters most against a physical damage dealer.

Take your trades near the wave: King's Tribute (passive) heals you for part of the max health of each enemy that dies near you, minions included.

Place Frozen Domain (W) where the fight will happen and draw the enemy into it: inside, you gain move speed, attack speed and increased healing.

Place Pillar of Ice (E) behind the fleeing enemy: it blocks their path and slows nearby enemies.

Cast Subjugate (R) on the enemy tank: you steal part of their armor and magic resist, and your team can focus them down.

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.