[quote=@Guardian Angel Haruki]
Dexterity Save...[@rush99999] Do I get advantage from Marine Layer? :3
[/quote]

I'm afraid not. The archers aren't aiming specifically at Cascade, they're firing to fill as much space with crossbolts as they can. So it's more a question of if Cas is dexterous enough to slip into the spaces where they can't put crossbolts. If you want advantage though, I believe Cascade has Inspiration.