A Horrifying Encounter

a Leviathan or a large scary looking creature with a special encounter in a very dark and deep biome, so dark that you can only see with flashlight equipment. The Leviathan/big creature wouldn’t be seen until the special encounter happens. It’d have an electric field of some sort that would turn off all equipment whenever you enter its domain except maybe a special flashlight item thats imune.

Once crafting the special flashlight, you could enter the biome and actually see (also entering it without it would leave you with no visibility until you die by said creature without seeing it at all). Going deeper into the biome, eventually all of your beacons would be glitched and you couldn’t view them. The only way to get out is to keep going further, or to turn around and try to make it back the way you came, without the beacons to help you. Eventually you’d see the creature or leviathan and have to sneak past it by turning off your light ( at this point in the biome there is some faint bioluminescant flora on the seafloor that you use to guide yourself).

Succesfully making it past the creature/leviathan would reward you with a base with advanced blueprints for powerful new items such as an upgraded wakemaker, maybe a few upgrade modules, and more. Also inside the base could be new story details about the people (or person) who made the base.