Immunity to Cold

A creature with cold immunity never takes cold damage. Even when subject to spells or abilities that reduce a monster's cold resistance, they will continue to remain immune to cold damage.

List of monster types that are immune to cold damage

 * Skeletons
 * Ice Mephits
 * Frost Giants

PnP Comparison

 * In DDO, creatures with Cold Immunity don't necessarily have vulnerability (+50%) to fire. Some do, but many such as Skeletons do not.