Chris Van Deelen

one knows why, not even the Undying themselves.

Finally both the regular undying and the feral undying cannot heal normally. They need radiation in order to heal any damage they have sustained, and it replaces their healing rate. For every class of radiation they are exposed to the Undying heal 1 hit point per 24 hours of exposure. For example, an Undying has sustained wounds in combat and finds a field of class 5 radiation. As long as the Undying stays in this field, it will heal 5 points of damage every 24 hours.

Mutations: Bizarre appearance(d), extended life span, immunity to radiation and all toxins, toxic weapon (disease).

Fallout series