Diana vs Yasuo

Hit with Crescent Strike (Q) before Lunar Rush (E): on a target marked with Moonlight, the dash has no cooldown and you can recast it right away.

Weave autos between your spells: after each ability, Moonsilver Blade (passive) boosts your attack speed for 5 seconds, and your third hit cleaves nearby enemies.

Cast Pale Cascade (W) before you engage: you gain a shield, then a second one when the last sphere explodes.

Cast Moonfall (R) in the middle of their team: it pulls in and slows nearby enemies, and hits harder for each champion pulled after the first.

Hit him with a cheap attack to trigger the Way of the Wanderer (passive) shield, then start the real trade: otherwise, it absorbs your best damage.

If you have projectiles, save them for after Wind Wall (W): it blocks them all for 4 seconds, on a 25 to 17 second cooldown. Other spells go through it.

Don't stand right behind your minions: each one gives him a target for Sweeping Blade (E), and he gets closer to you with every dash.

Get out of the line of his whirlwind, the third Steel Tempest (Q): without a knock-up, he can't cast Last Breath (R).

Judge his threat by his crit items more than his level: Way of the Wanderer (passive) raises his critical strike chance, so each crit item does more for him.