Jax vs Master Yi

Start your trades with Counter Strike (E): you dodge autos and take less area damage, and each dodged auto adds damage to the stunning counterattack.

Look for long trades: each consecutive auto increases your attack speed thanks to Relentless Assault (passive).

To escape, place a ward and jump to it with Leap Strike (Q): it can target any unit or ward, allied or enemy.

Activate Grandmaster-at-Arms (R) up close: it only grants armor and magic resist if it hits a champion, and your bonus hits then land every other auto.

Against Highlander (R), don't run alone: regroup with your team, because he gains speed and ignores slows.

If you have CC other than a slow, land it right after Alpha Strike (Q): during the strike, he's untargetable, and Highlander (R) ignores slows.

If you have CC, interrupt Meditate (W): he channels it to heal, more at low health, and to reduce the damage he takes.

Put pressure on his jungle early on: Master Yi is strongest once he has his items, and each stolen camp delays him.