Yasuo vs Kassadin

Hit twice with Steel Tempest (Q), on minions if needed, to charge the whirlwind. Cast it during Sweeping Blade (E): the strike becomes a circle.

Keep moving before taking a trade: Way of the Wanderer (passive) builds your shield while you move, and it triggers on the first hit you take.

Chain Sweeping Blade (E) on different targets to reposition or dodge: each target has its own cooldown, so the spell comes back almost instantly.

Save Wind Wall (W) for a projectile that decides the teamfight, like Jinx's ult, rather than for poke: it blocks for 4 seconds, on a 25 to 17 second cooldown.

Watch for your allies' knock-ups: Last Breath (R) can be cast on any airborne champion, whether the knock-up comes from your whirlwind or Malphite's ult.

Take as many trades as you can before he hits level 6: without Riftwalk (R), he has no way to move quickly, to engage or to escape.

If you deal physical damage, lean on it in trades: Void Stone (passive) and Null Sphere (Q) only reduce magic damage.

When he recasts Riftwalk (R) back to back, back off and drag the teamfight out: each quick recast doubles its mana cost, and once he's out of mana he can't blink anymore.

Look to end the game early: at max rank, Riftwalk (R) only has a 2-second cooldown, and he blinks almost nonstop.