Lux vs Miss Fortune

Start with Light Binding (Q), then Lucent Singularity (E) and Final Spark (R) before detonating the singularity: the root makes sure everything hits.

Slip in an auto after each spell that hits: it triggers Illumination (passive) for extra magic damage, and Final Spark (R) triggers it too.

Cast Lucent Singularity (E) into a brush before walking in: the area is revealed, and a hidden enemy would be slowed.

Cast Prismatic Barrier (W) through as many allies as you can: the wand shields them on the way out, then again on the way back.

Cast Final Spark (R) to clear a wave or secure an objective: it only has a 60 to 40 second cooldown, depending on rank.

Don't stay behind a low-health minion: if Double Up (Q) kills it, the bounce that hits you always crits.

Hit her regularly, even with a small hit: Strut (W) only grants her passive move speed after a few seconds without taking damage.

If you can engage, get on top of her: Miss Fortune has no dash or leap, only the speed from Strut (W).

If you have CC, save it for Bullet Time (R): she channels in place, and interrupting her cancels the remaining waves.