Knight of the frozen depths

the subclass has learned to harness the cold

Frost Warrior

At 3rd level, You gain resistance to cold damage. This becomes Immunity at 10th level.

You gain advantage on initiative in cold environments 

as a bonus action, you can invoke your frozen rites for the next hour. the Frozen Rites allows your attacks an 1d6 extra cold damage. this damage goes up as you level up 7th level (1d8) 11th level (1d10) 17th level (2d10).  you can use this ability once per short or long rest

Winter's Fury

at 7th level, when you land a successful attack have that creature make a constitution save. the  dc is equal 8 + your proficiency bonus + your Charisma modifier. on fail the creature freezes and become stunned until the end of your next turn , otherwise they lose half their movement. you may use this ability equal to your charisma modifier per long rest. This does not affect creatures with Immunity to cold and creatures with cold resistance have advantage on the save.

Armor of Blizzards

at 10th level, you gain the ability to cast armor of agathys at 1st level a number of times equal to your charisma modifier. the Components are not required for these uses. you may use multiple uses to up cast armor of agathys  up to 5th level.

Mist of Flurries

at 15th level you may create a mist in a 10ft sphere around you. creatures have disadvantage on attacks, loses 10ft of movement while in the area and for one turn after the exit the space, and takes 1d4 cold damage while in the space

at 18th level the sphere increases to 20ft and take 1d8 cold damage

Arctic squall

At 18th level, you may create a raging blizzard in a 40ft sphere for 1 minute , this is considered difficult terrain and enemy creatures have disadvantage on attacks. these creatures must make a constitution saving throw they take 6d8 cold damage on fail. on a successful save they take half damage. select allies do not gain these negative affects