Fume is an enemy found in the Research Facility in Sandia Jara. It can be fought in the last room after some cutscenes.
Cannot be damaged by poisoned characters. At battle start he'll poison the entire party including himself with Toxin Stream so you'll need to heal the status before attacking. When Fume is poisoned his health regenerates, so nullify him as quick as possible. He repeats Toxin Stream every 4 turns.
Turn 0x4 - Toxin Stream: Poisons the entire field
Turn 2x4 - Blind All: Blind on all enemies
Turn 3x4 - Asphyxiate: Instant fallen on one enemy
Asphyxiate Choke - Non-elemental magic damage with high variance to all. Formula: 850 + (a.mat * 4) Isolate - Ice damage on one enemy that causes confusion.