Yasuo vs Diana Mid Matchup

Why Yasuo is favored

Yasuo counters Diana because he dominates extended melee trades with manaless sustained damage once her burst rotation is spent, while Wind Wall blocks Crescent Strike to completely deny her Moonlight dash reset.

How to play as Yasuo

Hold Wind Wall strictly to block Crescent Strike: denying Diana's Q prevents her from resetting Lunar Rush and leaves her stranded in melee range without an escape.

Force extended melee trades when Diana dashes in: her damage drops sharply after her initial Electrocute burst and Pale Cascade spheres, allowing your continuous Steel Tempest to easily win the trade.

Wind Wall intercepts and destroys Crescent Strike on contact, preventing Diana from applying Moonlight and denying her Lunar Rush cooldown reset.

How to play as Diana

Never commit your all-in while Yasuo has both his Way of the Wanderer shield and whirlwind ready: his shield soaks your initial burst while his knock-up guarantees he turns the trade.

Bait out Wind Wall before committing Lunar Rush: if Yasuo blocks Crescent Strike, you lose your Moonlight reset and are trapped in melee against his superior sustained DPS.

Freeze the wave near your turret to starve Yasuo of minion dash targets for Sweeping Blade, setting him up for your jungler since Diana provides strong gank setup with Moonfall.

Lunar Rush and Moonfall are targeted dashes and area-of-effect pull-ins rather than missiles, so Yasuo's Wind Wall cannot block either ability.

Crescent Strike travels in an arced trajectory, allowing Diana to curve the path around the flank of an existing Wind Wall if angled wide.

Sources

These notes come from r/DianaMains, checked against the champions' abilities.