Miss Fortune vs Katarina

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.

Stay away from her daggers on the ground: when she picks one up, Voracity (passive) hits every nearby enemy, and Shunpo (E) lets her blink to it.

Trade right after Shunpo (E): it's her only blink, and it has a 12 to 8 second cooldown, less if she picks up a dagger.

If you have CC, save it for Death Lotus (R): it's a channel, and interrupting it stops its damage.

Don't count on your healing during Death Lotus (R): each knife applies Grievous Wounds, which reduces healing received.