Lava fume

Lava fumes were toxic gases emitted from lava lakes located deep underground on the planet Mustafar. When inhaled, the fumes played tricks on the mind, giving rise to voices and visions of fears and doubts that could manifest as ghosts of the past. Sustained exposure to the gases drove an organic sentient insane, and repulsor vents were thus installed at indoor facilities to prevent the fumes from being inhaled by those within. Lava-fumes drifted upwards to surface-level facilities, and were most potent around the vicinity of Fortress Vader and the Klegger Corp Mining Facility.

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