Jax vs Nasus

Start your trades with Counter Strike (E): you dodge autos and take less area damage, and each dodged auto adds damage to the stunning counterattack.

Look for long trades: each consecutive auto increases your attack speed thanks to Relentless Assault (passive).

To escape, place a ward and jump to it with Leap Strike (Q): it can target any unit or ward, allied or enemy.

Activate Grandmaster-at-Arms (R) up close: it only grants armor and magic resist if it hits a champion, and your bonus hits then land every other auto.

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.