Glacial Knight

Glacial Knights are fighters with an innate connection to the season of winter, a time cold waters and freezing temperatures. They are able to traverse the most harshest of tundras and mountains thanks to their connection, using it to explore to their hearts content. They can also imbue their attacks with frost, letting them extend the harsh winters domain to the battlefield.    

Biting Frost

Starting at level 3 you gain a connection to winter. When make an attack action, you may choose to imbue that attack with an icy vigor, adding a damage die (the die of the weapon used) of cold damage to the attack. You can use this feature a number of times equal to half your proficiency rounded down (a minimum of 1). Afterwards, the creature targeted has their speed reduced by 10 feet until the end of your next turn. This feature may only be used once per turn.

Frozen Protection

Your connection to winter grants you protection against it. You now have resistance to cold damage, and you no longer are negatively effected by difficult terrain that involves ice or snow. Additionally, you can extend this feature to up to 5 other creatures for an hour once per long rest, as you temperately connect them to winter.

Blizzard's Rebuke

Your powers grow ever so colder. At level 7, when you are hit by a weapon or spell attack, you can retaliate with the might of a blizzard. The target must make a Strength saving throw. On a failed save, the target is damaged with 3d10 cold damage and is thrown back 10 feet. On a successful save, the damage is half as much and they are not thrown back. This feature can only be used once per long rest.

Cold Empowerment

At level 10, your control over the cold has improved greatly. The following changes are made to your previous features.
Biting Frost. This feature now deals an extra damage die of cold damage.
Frozen Protection. The amount of hours you can connect your allies to winter with increases to 4 hours.
Blizzard's Rebuke. You can now use this feature two times per long rest.

Icy Winds

At level 15, you gain a small bit of control over the winter air, using it to hide your movements. The winds from this feature can pick up snow, snuff out fires, and create noise that makes it hard to hear any movements coming from you and those close to you for 5 minutes. While this feature is active, you have advantage on Stealth checks. You can use this feature a number of times equal to half your Fighter level rounded down per long rest.

Winter Savant

At level 18, you're a master of the ice and snow. Your Biting Frost feature now deals 3 damage dice of cold damage, and now the targets speed set to 0 feet, as they're legs are frozen in place, unable to escape your grasp.