Xerath vs Yasuo

Charge Arcanopulse (Q) to poke from long range: its range grows with the charge, but you slow down by up to 50% in the meantime.

Slow your target with Eye of Destruction (W) before Arcanopulse (Q): the center of the zone slows the most, and a slowed target dodges poorly.

Land Shocking Orb (E), then center Eye of Destruction (W) on the target: stunned, they can't dodge it, and the center slows the most.

Cast Rite of the Arcane (R) to finish a fleeing target or support a distant fight: your shots reach 5000 range, with bonus damage per champion hit.

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.