Fire Saboteur is a defense gear perk that improves both fire and poison defense. It covers two damage types that often show up together in the same fight.
You take less damage from fire and from poison. That covers burning ground, incendiary rounds and toxic gas.
A solid all-round pick when you face mixed elemental threats. Pure fire or poison perks give a bigger boost to one type.
Flame Retardant handles burning status, and Major Poison Protection stacks more poison defense.