Kai'Sa ADC vs Nautilus Support Matchup

Kai'Sa ADC wins 50.2% of 14,039 Low Elo games against Nautilus Support, -0.2 points vs expected, 2-patch window 26.19-26.20.

Researched on LoL patch 26.20. Tips are written to hold at any rank; stats come from Low Elo ranked games up to patch 26.20.

How to play as Kai'Sa

Stay behind your minion wave when Nautilus is looking for Dredge Line(Q); stepping to the edge of the wave can leave you exposed to the hook. (Unverified: no source confirms this note.)

If Nautilus hooks your support and Aftershock is active, attack the enemy carry if they are in range and you can do so safely instead of forcing damage into Nautilus. (Unverified: no source confirms this note.)

Before level 6, look to pressure Nautilus when Dredge Line(Q) misses and it is safe; after level 6, remember he can still engage with Depth Charge(R). (Unverified: no source confirms this note.)

How to play as Nautilus

After Kai'Sa lands with Killer Instinct(R), root her with Staggering Blow(P) or cast Depth Charge(R) if she is in range, then follow up with your team. (Unverified: no source confirms this note.)

Dredge Line(Q) expands slightly in radius at the very end of its range, allowing Nautilus to snag targets standing just adjacent to minion collision hitboxes.

When Nautilus takes Aftershock, immobilizing an enemy with Staggering Blow(P), Dredge Line(Q), or Depth Charge(R) grants him bonus armor and magic resistance for 2.5 seconds.

Depth Charge(R) tracks its target after cast and can knock up and stun enemies hit by the shockwave along its path and at the final impact; a spell shield can block the effect.

Sources

These notes come from LoL Wiki, checked against the champions' abilities.