Tryndamere vs Garen

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.

Hit him regularly, even with a small poke: Perseverance (passive) only regenerates him if he hasn't taken damage recently.

If you're ranged, kite him: his kit has no dash, and only Decisive Strike (Q) speeds him up and removes his slows.

Wait for the Courage (W) shield to end before your burst: the spell starts with a shield and tenacity, then keeps only a damage reduction.

Once he hits level 6, back instead of staying in lane at low health against him: Demacian Justice (R) deals true damage that grows with your missing health.