Miss Fortune vs Corki

Fire Double Up (Q) at a dying minion in front of a champion: if the shot kills the minion, the bounce onto the champion always crits.

Switch targets often: Love Tap (passive) adds damage on each new target, and lowers the cooldown of Strut (W).

Activate Strut (W) to get in position before Bullet Time (R): you instantly gain its max move speed bonus, plus attack speed.

Cast Bullet Time (R) on enemies who are CC'd or bunched up in a chokepoint: it's a channeled cone, and each wave can crit.

Don't count on your minions against Missile Barrage (R): each missile explodes on impact and damages enemies around it, you included.

Get out of the Gatling Gun (E) cone rather than trading inside it: it lowers your armor and magic resist while it fires.

Don't rely on a brush hit by Phosphorus Bomb (Q): the area and the champions hit stay revealed for a few seconds.

If you can engage, wait until Valkyrie (W) or Special Delivery is used: he's then vulnerable, with no way to reposition.