Kai'Sa vs Miss Fortune ADC Matchup

How to play as Kai'Sa

Avoid standing directly behind a low-health minion when Miss Fortune can cast Double Up(Q); if the first target dies, the bounce can critically strike its next target. (Unverified: no source confirms this note.)

Avoid repeated trades inside Make It Rain(E); look for a short trade after it ends, when nearby minions will not split Icathian Rain(Q). (Unverified: no source confirms this note.)

When Miss Fortune channels Bullet Time(R), use Killer Instinct(R) to move beside her and leave the bullet cone only if a visible champion is Plasma-marked and within your current rank's range; choose a safe landing point. (Unverified: no source confirms this note.)

Miss Fortune roots herself in place for up to 3 seconds while channeling Bullet Time(R); taking crowd control or issuing any movement command immediately cancels the channel.

Strut(W) passive move speed is immediately removed whenever Miss Fortune takes direct damage, allowing Kai'Sa's Void Seeker(W) or Icathian Rain(Q) to strip her mobility before a chase.

When Kai'Sa has no other nearby enemy units, Icathian Rain(Q) sends its missiles into Miss Fortune; nearby minions or champions can split the missiles and reduce the damage she takes.

How to play as Miss Fortune

Avoid channeling Bullet Time(R) at close quarters if Kai'Sa has Killer Instinct(R) available; bait her dash or wait until she is locked down by ally crowd control before channeling.

Sources

These notes come from LoL Wiki and r/missfortunemains, checked against the champions' abilities.