When I deactivate Density in Hero Lab, the Impervious ranks provided by the Density power still show up on the character sheet.
So if your character gets impervious from density and another power (Like Impervious Toughness) what you have showing on the character sheet may not be accurate.
So if your character gets impervious from density and another power (Like Impervious Toughness) what you have showing on the character sheet may not be accurate.