Your innate magic comes from a unique permanent mutation caused by imbibing a dangerously unstable ice leaf potion.

Ice Mutation

Due to your accidental mutation, you have mutated, and can pass as a Primordial of Ice.  You have a special affinity with the elements related to water. You can speak, read, and write Primordial and you double your proficiency bonus for CHA checks involving elementals, genesai, and other primordials.  You also double your proficiency bonus for CHA checks involving any other creatures that relate to water or cold.

Icy Resilience

The ice mutation affected your entire body, causing icy traits physically manifest. At 1st level, your hit point maximum increases by 1 and increases by 1 again whenever you gain a level in this class.

Additionally, parts of your skin are covered by a thin sheen of icy crystals. When you aren’t wearing armor, your AC equals 13 + your Dexterity modifier.

Ice Affinity

Starting at 6th level, when you cast a spell that deals Cold damage, you can add your Charisma modifier to one damage roll of that spell. At the same time, you can spend 1 sorcery point to gain resistance to Cold damage for 1 hour.

Frozen Fury

Starting at 14th level, dagger-like permafrost icicles begin to form all over your torso and shoulders.  When you are hit by a melee attack, you can use your reaction to deal cold damage to the attacker. The damage equals your sorcerer level. The attacker must also make a Constitution saving throw against your sorcerer spell save DC. On a failed save, the attacker has disadvantage on all weapon attack rolls , and loses 10' of movement speed,until the end of their next turn.

These icicles form over worn clothing and armor, and reform if broken or melted.  They can be shed by the sorcerer with little effort at any time.

Frost Aura

At 18th level, you gain immunity to cold damage and resistance to fire damage.

Your speed also increases to 60 feet, as you can slide and skate over any non-liquid surface. As an action, you can spend 1 sorcery point to freeze solid any liquids within 20 feet of you totaling 10 times your Charisma modifier gallons (minimum 10 gallons). The frozen liquid stays frozen as long as it is within 20 feet of you, unless some magical or extreme heat source affects it.