The character can eat anything, up to and including broken glass, and will suffer no more than one point of bashing damage as the “food” goes down. Anything less resilient than metal will be digested; things undigested will be passed, again causing no more than 1 point of bashing damage. They also receive one dot of the Hardy Merit for free, ignoring the normal prerequisites for it.
Drawback: Of course, with such a universal diet, one can always have... preferences. In this case, whenever they are hungry or thirsty, the character must succeed on a (Resolve + Composure) roll or else spend 1 Willpower not to eat any rotting meat or drink any stagnant, dirty water they see. They suffer a penalty on this roll equal to the Size of the rotting meat. Darkspawn with this Umbra almost always have Grotesque Bulk, and tend to make themselves larders of hung corpses (which need not be human; the first sign may well be all the pets going missing) in case they get peckish.