Lissandra vs Yasuo

Cast Ice Shard (Q) through a minion: the spear shatters on it, and its shards damage and slow the champion behind.

Engage from the flank with Glacial Path (E): recast it to blink to the claw, then root nearby enemies with Ring of Frost (W).

If you're getting focused, cast Frozen Tomb (R) on yourself: you become untargetable for a moment, heal based on your missing health, and the ice slows enemies around you.

Stay in the heart of teamfights: Iceborn Subjugation (passive) turns an enemy champion who dies near you into a Frozen Thrall, which slows, then explodes.

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.