The Trace On System, abbreviated as either TOS or TRON are a series of epidermal implants and nano-fiber filaments implanted to improve the reflexes, balance, and agility of the augment wearing them.
When was the last time a character caught a cold or flu? Real people get them every now and again even with solid heating and dry interiors. Your characters are out in the cold and wet, and even inside is not always dry and warm. Imagine having to stop your dungeon crawl, sitting in a tight defensive position, while you all are feverish.