You also can “capture” ritual that contain unique map boss by applying Ritual Vessel on the last activated-ritual spawn in your map, which would turn into a Blood-filled Vessel, just make sure the ritual does spawn the boss during your last ritual encounter when you wanna...
Now find out which map to farm each card in Path of Exile: PoE 3.25 Div Card Locations (Maps) Card NameDrop Location (Map) Blind Venture Relic Chambers Map, Sanctuary Map, Maze Map The Opulent Relic Chambers Map, Sanctuary Map, Vault Map The Lord of Celebration Relic Chambers Map...