Volibear vs Nasus

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.

Early on, take a trade whenever he steps up to last-hit a minion: each kill with Siphoning Strike (Q) increases its damage for the whole game.

Freeze the wave near your tower: to farm with Siphoning Strike (Q), he then has to step up and expose himself to ganks.

Once he hits level 6, don't engage during Fury of the Sands (R): for 15 seconds, he gains health and resistances, and his area damage scales with your max health.

In teamfights, if you're ranged, hit him while backing off: he has no dash, only Wither (W), a slow that grows stronger over time.