You belong to the Covenant of Primordial Elements, that being ICE, WATER, WIND, FIRE, EARTH, and LIGHTNING. Each primordial element has a host spellcaster that sees to the will of that element. The primordial elements have only one desire, to keep the elemental balance of the world in check and prevent terrible natural disasters that result from any unbalance (all primordial hosts possess this ability). The title of each element changes depending on the gender of host. While a Primordial element is a spirit of sorts, it can be very active in its hosts body or very little at all depending on the element. This one, the one belonging to ICE, prefers to give wisdom and occasionally defend its host. It is a passive spirit. The ICE element can be destructive and regenerative. 

The primordial hosts are a very closely guarded secret among the higher powers of magical society.  If their mission is found to be of a Primordial Elements design, not even royalty may obstruct their path. This privilege is rarely used as some additional people will know about a host.

There are many followers of the six elements and depending on your element, you may find assistance from these (per your DM if they allow it within the story).

Any fire spells you cast have disadvantage.

Words of Winter

Using your connection to your primordial element, you gain the ability to use the Shield spell reaction for free once per long rest. Additionally, it becomes Frozen Aura, gaining cold properties that can cause an enemy to take penalties on failed throws. (14 con ST) (At level 3 it becomes 2 free uses, Level 6 becomes 3 and the AC bonus becomes 6, 10 is an increase to 16 con ST). 

Additionally, if your terrain is cold, Shield becomes a cantrip until you leave the cold zone. This ability is unavailable in hot environments. 

You have resistance to cold spells.

Due to channeling spiritual ice energy, metal weapons' can not stand the cold focus of you magic unless they are specially made to. As a counter balance, you can create a temporary replica ice version of the weapon as long as you have proficiency in with it. It has the same stats as that weapon would have and lasts until the encounter is over. This ability is also unusable in hot environments.

Resonance

At 6th level you exude an aura of frost that grants nearby party members within 45 feet frost resistance. Additionally, when you use shield as your reaction affect, it grants its effect to an additional nearby party member as well.

Winter Wonderland

At 10th level, you gain the ability to terraform the area around you into a frozen tundra. This can only be used once per long rest and effects approximately 100 feet all around you. The effect also creates 8 icy pillars which count as cover.

All enemies must make a dexterity saving throw when moving within the tundra or they will move uncontrollably within it. Allies within the tundra gain the temporary equipment, Icy Skates. While equipped with these, they gain the ability to travel an additional 15 feet within the tundra and no longer need to make dexterity saving throws while moving in the tundra.

The area around you becomes a cold environment.

Each turn, you may snap your fingers and destroy one of the ice pillars. Allies caught in the misty after effect will be healed 5d12 damage and enemies caught in it will be blinded for 1 turn.

Infusion

At the 18th level, you gain the ability to channel your Primordial elements spirit magic to its fullest. You may infuse with it three times per long rest. Each infusion lasts two turns and while infused, shield becomes a cantrip and effects the entire party when used. Additionally, when using shield, it will heal 5D12 hit points worth of damage.

Additionally, at the 18th level, all ice spells aimed at you now heals 1D8 hit points instead of causing damage. You also can not be frozen and Icy terrains are no longer difficult terrain.

Your natural AC is increased by 5 and you can create ice bridges over small bodies of water.