Vulnerability to Cold
Some creatures have vulnerability to a cold. Such a creature typically takes half again as much (+50%) damage as normal from the effect, regardless of whether a saving throw is allowed, or if the save is a success or failure.
Examples of monster types that are vulnerable to cold damage
Some creatures, such as Fire Mephits are exceptionally vulnerable to cold and take double damage (+100%) from cold effects.
See also: Category:Vulnerability to cold monsters