The Traveler's Ring can be found in the campaign Under the Burning Suns, in the 2nd scenario Across The Harsh Sands.
One unit wearing this ring is immune to any damage caused during the day by the heat of the desert.
It looks like a tiny gold ring. I think I see elvish runes on the inside, but I can barely make them out. This seems to be a ring of travel! Those who wear it will not suffer from thirst or hunger, nor cold, nor heat. I’ve heard tales of such magical items. ~Kaleh~