Cho'Gath vs Master Yi

Aim Rupture (Q) where your opponent is going, not where they are: the area knocks them into the air and slows them.

Follow a successful Rupture (Q) with Feral Scream (W): the silence stops them from casting spells, dashes included.

Cast Vorpal Spikes (E) before a trade: your next 3 autos launch spikes that slow enemies in front of you and deal damage based on their max health.

Finish with Feast (R) as soon as it's up: each kill gives you permanent max health, but minions and non-epic monsters only give a limited amount.

Against Highlander (R), don't run alone: regroup with your team, because he gains speed and ignores slows.

If you have CC other than a slow, land it right after Alpha Strike (Q): during the strike, he's untargetable, and Highlander (R) ignores slows.

If you have CC, interrupt Meditate (W): he channels it to heal, more at low health, and to reduce the damage he takes.

Put pressure on his jungle early on: Master Yi is strongest once he has his items, and each stolen camp delays him.