Retrieve the Soapstones from the Hermit.
Place the soapstones on the ground in the square shaped outlines between the Boathouse and the Lighthouse.
Activate the Lighthouse trap near the Boathouse. The soapstones should be heated.
Without touching water, make your way to the Facility. Place a soapstone in the control panel in Human Infusion. Place the other soapstone on the square outline in the Ice trap in Decontamination.
Activate the Ice trap. Collect the frozen soapstone and place it in the control panel. The fuse should be unlocked.
Use the Wunderwaffe DG-Scharfschutze and shoot down two red batteries on a power line above the facility.
Power 3 generators by killing electric zombies near them. The generators are at Boathouse, Lighthouse Station, and Lighthouse Approach.
Interact with the power next to the mechanical door in the Lighthouse Station.
Collect the Elemental Shard from behind the door.
Repeat step 3. Shoot the blood until orange orbs scatter around the map, freeze the orbs, return and freeze the orbs again, place the seal on the campfire and throw a Samantha's Music Box at it, then collect the Seal of Duality.