Whether due to your bloodline, the circumstances of your birth or a hex cast upon you, you have a deep and intense connection with the frost and all things cold. Because of this, a blizzard rages inside you, forcing itself out through your magic. 

Heart of Winter

Ever since you were born, you've been well aquatinted with the ice and snow. You know the Ray of Frost cantrip and ignore difficult terrain imposed by ice or snow. Additionally, being in severe cold doesn't effect you unless it's magical induced.

Mark of Frost

Your proficiency in creating magical ice allows you to force the ice to linger after the spells effects end. Whenever you deal cold damage to a target with a spell of 1st level or higher, you can choose to mark them with frost. The next time the target is hit with an attack or spell, the mark shatters and deals damage equal to the original spells level + your proficiency bonus. You can use this feature a number of times equal to your proficiency bonus per long rest.

Frost's Blessing

Your connection to the cold has begun to envelope your soul. Beginning at 6th level, you gain resistance to cold damage. Additionally, any creature marked with your Mark of Frost loses resistance to cold if it has one, and any creature that breaks the mark gains temporary HP equal to the damage dealt by the mark.

Staggering Chill

Your magical ice has become potent enough to freeze targets in place. When you deal cold damage to a target, they must make a constitution saving throw against your spell save dc or have their movement halved, as well as having disadvantage on dexterity checks and saving throws until the end of your next turn.

Snow Cloak

You've become fully one with the blizzard within your soul, allowing you to manifest it into reality whenever you call upon it's power. You gain immunity to cold damage and treat other creatures cold immunity as resistance instead. Additionally, whenever you cast a spell that deals cold damage, you can choose to make a blizzard form around you in a 10 ft radius. This blizzard lightly obscures you, counting as partial cover, and any creature of your choice that ends it turn in the radius takes cold damage equal to your sorcerer level + your charisma modifier. This Blizzard lasts 1 minute, and can be used one per long rest.