Sylas vs Yasuo

Weave an auto after each spell: Petricite Burst (passive) turns it into a chain swing around you, with bonus magic damage.

Save Kingslayer (W) to finish or to save yourself when your health drops: its healing grows with your missing health.

To engage, cast Abscond (E), then recast within 3.5 seconds: Abduct (E) pulls you to the first enemy hit and knocks them into the air.

Cast Hijack (R) on the enemy whose ult can turn a teamfight: you keep a copy of it, cast with your own stats.

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.