Brume Beast originated from the coalescence of ancient creek mist and primal fears, forming when supernatural fog reached critical density during upstream disturbances. It emerged as a protector of the fog-shrouded waters, gaining sentience from territorial conflicts between creatures and humans. Over time, it became a permanent entity in the creek's ecosystem, lurking within the densest fog banks.

Brume Beast possesses a semi-corporeal form that blends with fog, allowing it to shift density and visibility at will. It can manipulate fog patterns to disorient prey, emitting low-frequency growls that vibrate through the mist. Its body is resistant to physical attacks due to its gaseous nature, but it weakens in direct sunlight or strong winds. The beast moves silently through fog banks, leaving no traces except for sudden temperature drops and condensed moisture.

Brume Beast acts as an ambush predator that uses fog as hunting grounds, striking when visibility is lowest to isolate players and escalate fear during fog-based events.