Shivers are Silvers who can decrease temperature, with their mind. However, their ability isn't limited only to freezing and frost inducement. They are capable of turning moisture into ice structures. They are immune to cold. They can generate cold breaths, who freezes anything with a great reach. They can freeze anything they touch.
"Shivers are elementals, manipulators of temperature and cold, able to freeze things dependent on properties of the target. Most shivers can easily manipulate water or more stable liquids into ice." - On Silverblooded Abilities by Victoria Aveyard