Volibear vs Master Yi

Cast Thundering Smash (Q) to charge at your target: your speed doubles when heading toward a champion, and your next auto stuns them.

Hit the same target twice with Frenzied Maul (W): the second hit, on the marked target, hits harder and heals you based on your missing health.

Cast Sky Splitter (E) where you're fighting and stay in the zone: when the lightning strikes, you gain a shield, and enemies hit are slowed.

To dive under a tower, cast Stormbringer (R) near it: on landing, you disable it for a few seconds, and you gain bonus health.

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.