Immunity to Metabolic Hazards and vices

[Kromm]

ItMH means that no chemical, disease, or similar agent that alters your metabolism to cause the afflictions on pp. B428-429, or indirect FP or HP loss, affects you. This includes ones that word their afflictions as temporary disadvantages. The advantage is entirely blind to "intent." The difference between mental effects from alcohol consumed in a cocktail and very similar ones from exposure to certain toxic gases you might be exposed to as weapons is irrelevant. If you want to gimp your advantage to have one specific recreational toxin affect you, that seems like a fair quirk. Likewise, if you want your advantage to be switchable with respect to one specific agent, that seems like a fair perk.