Legendary Resistance (2/Long Rest). If Yasuo fails a saving throw, he can choose to succeed instead.
Way of the Wanderer. Yasuo is the last man to master the Wind Technique, an ancient swordstyle that commands the wind as a deadly tool. Yasuo has the following benefits:

• Yasuo's attacks with Steel Tempest generate a stack of Gathering Storm when they hit, stacking up to 2 times. At 2 stacks, Yasuo's next attack conjures a 15-foot radius tornado that travels in a 60-foot long line, until it collides with a large structure, or a Huge or larger creature.
• Intent: Yasuo critically strikes on a roll of 18-20 on the d20.
• Resolve: Yasuo generates Flow when moving and attacking. Every attack and 10ft. of movement generates 10 flow. At 100 flow, the next instance of damage taken grants 30 (5d10) temporary hit points. Any remaining temporary hit points are lost at the start of Yasuo's next turn.
• Mobile: Yasuo has a 10-foot bonus to his walking speed. Additionally, Yasuo doesn't trigger attacks of opportunity from creatures if he has made an attack against them this turn whether he hits or not.

Multiattack. Yasuo makes three Steel Tempest attacks.

Steel Tempest. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 16 (2d8 + 6) piercing damage.
Gathering Storm: All creatures must succeed a DC 17 Strength saving throw or be launched 30ft airborne and take 16 (4d6) thunder damage and land prone. Creatures take half as much damage and are not flung airborne on a success.

Second Wind (Recharges after a Short or Long Rest). Yasuo regains 30 hit points.

Sweeping Blade. Yasuo dashes through the space of a creature in range attacking with Steel Tempest (+11to hit, 10 (2d8) slashing damage) once. If Gathering Storm has 2 stacks, Yasuo creates a stationary, 15-foot radius, tornado instead of a 60-foot long line.

Wind Wall (Recharge 5-6). Yasuo swipes his blade at the ground beside himself, creating a large wall of wind, similar to the wind wall spell, to shield creatures from incoming ranged weapon and spell attacks. The wall gives large projectiles(siege and boulders) disadvantage instead of automatically missing. The wall dissipates at the start of Yasuo's next turn.

Last Breath (Recharge 6). Yasuo targets up to five airborne creatures he can see within 60ft. of him and blinks to them. Make a Steel Tempest (+11) attack against each target with advantage. On a hit, a target takes 36 (6d10) slashing damage. Additionally, for the next minute, Yasuo's attack rolls ignore 2 AC.

Yasuo can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. Yasuo regains spent legendary actions at the start of his turn.

Hasag! Yasuo makes one Steel Tempest attack.
Sweeping Blade. Yasuo chooses a creature to dash to which he has not targeted this round.
Aseryo! (Costs 2 Actions). If Gathering Storm has 2 stacks, Yasuo uses Steel Tempest to conjure a tornado.
Gathering Winds (Costs 2 Actions). Yasuo generates 30 Flow. Yasuo may also attempt to recharge Wind Wall.
SORYE GE TON (Cost 3 Actions). Yasuo recharges Last Breath.