Tryndamere vs Nasus

Keep your Fury high before a trade: with Battle Fury (passive), it raises your critical strike chance. Spend it with Bloodlust (Q) when you need health.

Cast Mocking Shout (W) before a trade against a physical damage champion: it lowers their attack damage, and slows enemies who turn their back on you.

Count on Spinning Slash (E) to stick to your target or to escape: each critical strike lowers its cooldown, more so on a champion.

Wait until you're close to death to cast Undying Rage (R): you can't die during the effect, and delaying it pushes the enemy to take risks to kill you.

Split push in a distant lane to draw several enemies: Undying Rage (R) helps you hold them off while your team takes an objective.

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.