Frozen bloodline

The patches of frost on their body coupled with their icy blue/white eyes give a clear indication of someone being a sorcerer from a frozen bloodline. Usually these sorcerers can trace back their bloodlines to pacts, curses or bonds made with gods and goddesses of ice, Frost giants or maybe a even a witch of frost from the far north. Their bodies are coated in a light layer of frost, their breath foggy, and their eyes bright blue/white. Depending on the individual their hair might be turned silver by the frost covering their bodies. 

Frozen bloodline sorcerers are feared in certain areas as signs of disastrously cold winters and so prefer to mostly keep themselves away from the rest of civilization and create their own small nomadic communities, usually only housing a few denizens.

Your adventurer may be a survivor of a destroyed community, a tribesmember struck with wanderlust or a sorcerer new to his powers.

Expanded spell list

Your frozen blood lets you choose from an expanded list of spells when you learn a warlock spell. The following spells are added to the sorcerer spell list for you.

spell level	Spells
Cantrip	Frostbite, Ray of frost
1st	Ice knife, Fog Cloud
2nd	Snilloc's Snowball Swarm, Spike Growth
3rd	Sleet Storm
4th	Ice Storm, Elemental Bane
5th	Cone of Cold
6th	Wall of Ice

 

Freeze the waters

At first level you learn the Shape Water cantrip, which counts as a sorcerer cantrip for you. Additionally you may freeze up to 10 cubic feet of water instead of the regular 5.

Frozen body

Beginning from 1st level your body becomes partially frozen

As the ice cold Blood courses through your veins, your flesh partially freezes, giving you resistance to cold damage and an AC of 13+dex while you're not wearing armour. Additionally you can ignore rough terrain caused by snow or ice.

Frostbite

Beginning at 6th level You can use a sorcery point to change a spells damage type to cold

Additionally any time you use a spell that deals cold damage you can add your charisma modifier to the spells damage roll.

Glacial body

At 14th level your flesh becomes completely frozen, Granting you the following of abilities:

• Glacial flesh: Your aging slows down drastically thanks to the preserving effects of the frost that surrounds you. You age 5 times slower and can't be aged magically.
• Immune to cold: Cold no longer phases you, you become completely immune to cold damage.
• Shield of frost: When you get hit by a cold spell, roll 2d6 and add the result as temporary hit points
• Chilled to the bone: When you deal cold damage you can ignore resistance and treat cold immunity as cold resistance

Absolute zero

starting at 18th level you can tap into the full power of your frozen blood

As an action you can spend 10 sorcery points to create a blast of freezing energy in a 30 foot radius around you. Any creature caught in the blast must make a constitution saving throw, on a succesful save they take half damage, on a failed save a creature takes 8d10 cold damage and is stunned until the end of their next turn