Yasuo & Yuumi Synergy

Why this duo works

Yuumi makes Yasuo's melee engages safer: attachment keeps her out of danger, while Zoomies shields and speeds him and Prowling Projectile slows targets he can chase. Yasuo bot players describe Yuumi as a strong partner for the level 6 all-in; the +5.0pp low-elo effect is consistent with that protection and sticking power, while the high-elo effect is neutral.

Playing the duo

Yuumi's Zoomies gives her attached Best Friend a shield and movement- and attack-speed boost. Yasuo's Steel Tempest cooldown scales with attack speed, so the buff helps him cast Q more often while giving him extra protection to commit.

Prowling Projectile slows an enemy and helps Yasuo stay in range for Sweeping Blade. Final Chapter roots enemies but does not knock them airborne, so Yasuo still needs his own Steel Tempest whirlwind or another knock-up to cast Last Breath.

How to play as Yasuo

Let the wave come toward your tower and avoid losing health before level 3. Once you have your dash and Wind Wall, use Yuumi's shield and speed to take longer trades; at level 6, build your own tornado before looking for Last Breath rather than expecting Yuumi's ultimate to knock enemies up.

How to play as Yuumi

Stay attached through early poke and save Zoomies to shield and speed Yasuo as he commits. Use Prowling Projectile to slow his target, then cast Final Chapter after his engage to add follow-up control; coordinate his own tornado if he wants to use Last Breath.

Sources

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