What effect does the phrase "mortal coldness" convey in a narrative?

The phrase "mortal coldness" conveys a sense of dread, as it combines the concept of death ("mortal") with an emotion typically associated with fear or foreboding ("coldness"). When used in a narrative, this phrase suggests a chilling atmosphere or an ominous feeling that something bad may happen. This stark imagery evokes discomfort and anticipation in the reader, effectively setting a tone that reflects danger or the severity of a situation. Such language enriches the narrative by engaging the audience's emotions and heightening the impact of the scene being described.