9th level evocation You unleash a flurry of extreme cold in a 45 foot radius sphere centered on a point within range. Each creature in that area must make a Constitution saving throw, taking 3d12 cold damage and 3d12 slashing damage on a failed save as it is battered by cold winds and icy particles, or half that on a successful save. Additionally, the ground in that area becomes difficult terrain for the duration. If a creature moves into the affected space for the first time on its turn or starts its turn there, it must make the saving throw again.
If a creature spends three or more consecutive turns fully within the area and it fails its saving throw against the spell, it begins to freeze and becomes restrained. It must repeat the saving throw at the end of its next turn. On a success, the effect ends and it must spend another three turns in the area in order to trigger this effect again. On a failure, the creature is petrified for 1 hour after the spell ends, or until freed by the greater restoration spell or other magic. For the duration, you can use your action to move the sphere up to 20 feet.
If you maintain concentration for the entire duration, the sphere shatters and spreads. In a 10 mile radius around the sphere, the area becomes extreme cold for 7 days unless magic of 9th level is used to reverse it.
"Cold March" by Andreas RochaAbsolute Zero
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