Gwen vs Yasuo

Land 4 autos before Snip Snip! (Q): each auto adds a snip, on top of the first and the last.

Land the center of Snip Snip! (Q): in the center, part of the damage becomes true damage and each snip applies A Thousand Cuts (passive).

Place Hallowed Mist (W) against poke and ranged CC: enemies outside the mist can't target you, except towers.

Cast all three Needlework (R) activations within 6 seconds: the first throws one needle, then three, then five, with growing damage.

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.