Jellyfish Defender is a defense gear perk that improves poison and fire defense. It covers two elemental threats in one gear slot.
Poison clouds and fire hurt you less. You can push through toxic gas and burning ground with less risk.
A good flexible pick. Dedicated Major perks are stronger if you only face one of the two.
Flame Retardant puts out flames on you, and Major Poison Protection stacks more poison defense.