Monks who follow the Way of the Winter Warrior train in the harshest parts of the world, particularly those subject to year round freezing conditions. These disciplined fighters hone
their skills to become defensive combatants capable of withstanding extreme punishment from the large and dangerous creatures native to polar environments.  The most famous school of Winter Warriors in Faerun were the Brothers of Xidar. Now extinct, this exclusively dark elf (or "drow" as the Rasgax call them) monastery created hundreds of monks who followed this tradition until they mysterious vanished sometime around 500 AT.

Cold Strike

Starting when you choose this tradition at 3rd level, whenever you take the Dodge action on your turn, you can use your bonus action to make one unarmed strike.

Winter's Armor

At 3rd level, you can use an action to spend 1 ki point to encase yourself in a protective layer of hard ice. You gain 4 temporary hit points per level in this class. While active, you gain immunity to cold damage and vulnerability to fire damage. The ice lasts for 10 minutes or until you lose all your temporary hit points. When you reach 6th level in this class, you can spend 2 Ki points to increase the duration to 1 hour, and when you reach 11th level in this class, you can spend 3 Ki points to increase the duration to 8 hours.

Fog of Frost

At 6th level, you can use your bonus action to spend 2 Ki points to create a chilly fog with a 10ft radius centered on you. The area inside the fog is lightly obscured. While the fog is active, any hostile creature that ends its turn in the fog must make a Constitution saving throw against  your Ki save DC. On a failed saving throw, a creature takes cold damage equal to your martial arts die and its movement speed is reduced by half until the end of its next turn. On a successful saving throw, the creature takes half as much damage and its movement isn't affected. The fog lasts for as long as you concentrate (as if concentrating on a spell), up to 1 minute.

Ice Shield

At 11th level, when you are hit by an attack while using your Winter's Armor is active, you can spend 1 Ki point as a reaction to create a shield of solid ice. Until the start of your next turn, you have a bonus to AC equal to your proficiency bonus.

Cold Absorption

At 17th level, you gain immunity to cold damage, even while you aren't using your Winter's Armor feature. Whenever you are subjected to cold damage, you can spend 1 Ki point to absorb the damage. When you do, you take no damage and instead you regain hit points equal to the damage dealt.