|“||A lead-forged key with the symbol ♄ carved into it. This symbol means "Saturn."||”|
The Saturnus Key is a key in Haunting Ground. It is found in the Chapel. Fiona Belli finds this key hanging from a stone statue of Hermes and retrieves it just before encountering Debilitas and triggering a boss battle.
The key unlocks the door in the room above the Lunar Refractor puzzle room and leads Fiona down a flight of stairs towards the Mansion.