Master Yi vs Warwick

Cast Alpha Strike (Q) to dodge a spell or a burst: you're untargetable during the strike, and your autos lower its cooldown.

Cast Meditate (W) to tank a burst mid-teamfight: you take less damage, heal more at low health, and the time left on Highlander (R) is paused.

Activate Highlander (R) to chase: you gain move speed and attack speed, and slows no longer affect you.

Chain kills in teamfights: each takedown lowers the remaining cooldown of your basic spells, and extends Highlander (R) if it's active.

Keep your health above 50%: below that, Blood Hunt (W) gives him speed toward you and attack speed, three times more below 25%.

When he drops below 50% health, finish him fast, with CC if you have any: Eternal Hunger (passive) then heals him with each auto, three times more below 25%.

If you have a dash, don't count on it to escape his held bite: Jaws of the Beast (Q) makes him follow all your movement, then leap behind you.

In teamfights, stay behind your tankiest allies: Infinite Duress (R) suppresses the first champion hit, and its range grows with his move speed.

If you have Grievous Wounds, apply it to him: his autos heal him at low health, and Infinite Duress (R) heals him for all the damage it deals.