Place the Seal of Duality on the Blood.
The Blood will fly around the room, you must do damage to it until three orange orbs depart the Blood.
The 3 orange orbs will relocate across the map, you must hit them each with a snowball and then shoot them. There is generally one orb at the facility, one orb near spawn room, and one orb near the beach.
The orbs will fly back to Artifact Storage, you must hit them each with snowballs and shoot them once more. After that is done, collect the Seal of Duality.
Place the Seal of Duality on the campfire in the Sunken Path and throw a Samantha's Music Box on the campfire. There will be a few minutes of dialogue, pick up the Seal after it finishes.