Zed vs Master Yi

To kill, cast Death Mark (R), then Living Shadow (W), Shadow Slash (E) and Razor Shuriken (Q): with two shadows, you throw three shurikens.

Cast Death Mark (R) just as the enemy casts their decisive spell: during the dash, you're untargetable.

After Death Mark (R), save the recast to get out: you swap places with the shadow left at your starting point, far from the fight.

Save enough energy for a full combo rather than casting your spells for nothing: Living Shadow (W) refunds energy when you and your shadow hit the same target.

In teamfights, go around the sides and save Death Mark (R) for an isolated target: going in from the front exposes you to the whole team's CC.

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.