The wearer can cast Frostbite at will. Once per long rest, the wearer can also activate the ring to encase themselves in a protective shell of ice for 1 minute, granting +2 to AC and resistance to cold damage, but reducing speed by 10 feet.
The shell shatters early if the wearer takes 20 or more damage from any type of damage (except cold, psychic, or poison) or 10 or more damage from bludgeoning or fire.