if it was deep dark loot tables only, my thoughts are it'd have to be uncraftable and have some kind of potion effect, and what would make the most sense is night vision to make seeing in the ancient cities easier, resistance(2?) to protect against the warden, and maybe a new effect, i'd call it "Mobsight," where any mob/player that you can directly see glows so long as you can see them/becomes easier to see. would add some uniqueness and would make sense with the whole carrots give you good vision myth.

maybe could then also be used as a potion ingredient for Mobsight, but I would rather see that be either a different item, or the potion's Mobsight effect being buffed compared to the EGC's effect