A cold like never before blanket the earth in a 100 ft cube around the caster. Each creature of your choice within the cube must make a Dexterity saving throw. The effect of the spell goes around corners and through all open spaces. A creature caught in the spells area takes 20d10 cold damage, or half as much on a failed save and the ground effected becomes iced over by a biting cold. 

Any creature besides the caster that begins or ends there turn in the biting cold must make a Constitution saving throw or take an additional 3d6 cold damage, ignoring immunity to cold damage. The biting cold lasts for three days and kills all plant life in the area. Nothing beside a casting of the wish spell can dispel the biting cold.