Curse of Planar Ice

You curse a target creature that you can see within range, causing the liquid in its body to suddenly freeze. The target immediately takes 8d6 + 10 cold damage as crystalline needles erupt from its body, and its movement speed is halved for the duration of the curse. 

At the beginning of each of its turns, the cursed target makes a Charisma saving throw. On a failed save, the target immediately suffers an additional 2d6 cold damage as it continues to freeze, and it may make either an action or a bonus action on its turn, but not both. If the target succeeds on the saving throw, the extreme chill of the curse is momentarily abated. If the target succeeds on three saving throws, the curse immediately ends. These successes do not need to be consecutive, but if it fails three saves in a row, it loses all recorded successes and must start again.

If a creature dies while cursed in this way, its body twists into a pose of your choosing and is completely transformed into solid, opaque ice, with its soul is trapped within the statue. The creature cannot be restored to life by any means short of a wish spell, and cannot become an undead of any description so long as its soul is trapped within the statue. If the statue is destroyed, the soul is as well. The statue is vulnerable to fire damage, has resistance to magical bludgeoning and piercing damage, and is immune to all other forms of damage. It has an AC of 5, and 30 hit points. The statue loses 1 hit point at the end of each minute if it is not in extreme cold, or twice that if it is in extreme heat.

When you cast this spell as a ritual, the range of the spell becomes 300 feet, and you do not need to be within line of sight with the target. However, the spell requires 200 gp worth of expensive inks with which to draw a planar sigil on a flat surface, and which the spell consumes.