Sejuani vs Cho'Gath

Land both Winter's Wrath (W) swings: the second deals most of the damage and slows, and each one applies a Frost stack.

Cast Permafrost (E) as soon as your target has 4 Frost stacks: Winter's Wrath (W) and your melee allies' autos apply them.

Hit a target you just stunned: Fury of the North (passive) shatters them for heavy magic damage.

Engage with Arctic Assault (Q): enemies you pass through take a knock-up, and the charge stops on the first champion hit.

Cast Glacial Prison (R) at their carry from far enough away: past a quarter of its range, the stun lasts longer and a storm slows nearby enemies.

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.