Frostmancer

As a frostmancer, you call upon the power of ice and snow. With winter fueled magic, frostmancers cleave the warmth from their foes bones, and trap them in their icy tombs.

Freeze

Starting at 2nd level, you have gained the ability to turn small amounts of water into ice. As an action, you can freeze a 5 ft. cube of water within 30 ft. of you.

Frost Cage

Starting at 2nd level, you have learned to encase your enemies in frost. You add the Armor of Agathys spell to your spellbook if it is not there already. When you cast Armor of Agathys, you can cast it on another creature with the range of touch. When you cast it in this way, the creature's speed is halved and it takes 5 cold damage at the start of each of its turns while the spell is active. When it takes this cold damage, the damage targets the creature's HP, and does not effect the temporary HP that is given by the spell. 

The damage that another creature takes from this feature is increased by 5 at 6th level (10), 10th level (15), and 14th level (20).

Path of Ice

Starting at 6th level, moving on snow and ice does not affect you.

In addition, a number of times per long rest equal to your Intelligence modifier, as an action on your turn, you can move up to your movement speed. While you move in this way, any ground that you come within 5 ft. is covered in ice for 1 minute. The ice is difficult terrain, and when a creature moves on the ice for the first time on a turn, it must succeed on a DC 10 Dexterity (Acrobatics) check or fall prone.

Cold Accustomed

Beginning at 10th level, you gain resistance to cold damage, and your concentration cannot be broken by a snow or ice storm.

Icy Shell

When you roll initiative, if you are not surprised, you can use your reaction to cast Wall of Ice, even if it is not in your spellbook, although it still requires a spell slot. 

Once you use this feature, you cannot use it again until you finish a long rest.