Your technique is beautiful in its simplicity, and the ability to make and control ice.
Cursed Energy
Starting at 1st level, you can harness your negative feelings into a usable source of energy, called cursed energy. These feelings can be harnessed into attacks or abilities. The number of cursed energy you possess is based on your class, some classes use a modifier that being charisma or wisdom (Player’s choice)
Your cursed energy DC is 8 + user cursed energy ability modifier + proficiency bonus.
Ice Creation
Beginning at 1st level, your innate technique has allowed you to mess with the temperature around you, creating extreme levels of cold. As an action for 1 cursed energy, you can force every creature in a 10ft. cone to make a Dexterity saving throw. On a failure, they take 1d10 cold damage and are restrained as ice covers part of their bodies. On a success, they take half as much damage and are not restrained.
The creature may make a Strength saving throw at the beginning of its turns to break the ice and end the restrained condition.
All ice created by your technique will last until you end it at will, a creature breaks it, or you receive poisoned, paralyzed, stunned, petrified, or unconscious conditions.
At 3rd level, the damage of this feature increases to 2d10, to 3d10 at 6th, to 4d10 at 10th, to 5d10 at 14th, and to 6d10 cold damage at 20th level.
Extreme Cold
At 3rd level, being stuck on your ice feels like staying in a cold mountain while you wait for death. A creature inside your ice is under one additional level of Exhaustion. Any creatures within 5ft. of your ice that don’t have cold resistance or immunity have their movement speed halved.
Frost Calm
When you reach 6th level, you have learned how to unleash thick layers of ice through the mist. As an action for 4 cursed energy, you can send a cloud of freezing mist to a spot within 60 feet of you. Every creature in a 30-foot radius circle in that spot must make a Dexterity saving throw. On a failure, they take 7d8 cold damage and are restrained by the ice layer formed in the square. On a success, they take half as much damage and are not restrained.
The creature may make a Strength saving throw at the beginning of its turns to break the ice and end the restrained condition.
Ice Fall
Once you reach 11th level, you learn a great execution method that makes sure your enemies won’t escape. As an action for 8 cursed energy, you will become prone until the beginning of your next turn to create ice on the ground. You telepathically manipulate the ice created, launching one for every creature within 30ft. of you of your choice. Make a cursed energy attack roll, on a hit they take 1d10 cold damage and become restrained.
The creature may make a Strength saving throw at the beginning of its turns to break the ice and end the restrained condition.
Hitting or missing, giant spikes of ice will fall from the sky on top of the targeted creatures, forcing them to make a Dexterity saving throw. On a failure, they take 6d8 cold damage and 6d8 piercing damage. On a success, they take half as much damage.
Domain Expansion: Ice age
If you achieve 18th level, you hone your technique to a fine edge, allowing you to use your Domain Expansion. While inside it, every creature except you must attempt a Constitution saving throw at the end of each of their turns. On a failure, they take 10d8 cold damage. On a success, they take half as much damage.