Eternal Winter

This spell creates a snowstorm that will grow to massive proportions and cause an eternal winter.  This can only be dispelled with dispel magic when it is being cast.  Anyone not sheltered will slowly die of cold damage.  Fire damage is muffled and it is unable to be reversed with a spell that says it can reverse it.  While this event is occurring, everyone that isn't immune to fear will become frightened until the spell is dispelled.