Glacial Coffin

You fire a ray of ice at a target within range of the spell. The target must make a Constitution saving throw. On a failure, the target becomes encased in a permanent block of ice, leaving it Petrified.

The ice block is immune to all damage except true damage; while inside the ice block, the creature becomes immune to any spell cast upon it. Attempts to dispel magic are made with disadvantage. The caster of the spell can undo it at any time.