Settling thunderheads and crystal snow begins to whip through the air, moved by a sudden chill wind. A wave of biting cold air burst forth in a shrieking wave as the cold rath of ten arctic blizzards burst forth in a vengeful storm, smothering all in a seemingly endless biting cold. The storm expands 50 feet in radius from the castor every turn to a maximum radius of 200 feet. Each round you maintain this spell, the storm produces additional effects on your turn.

Round 1. Icy Permafrost springs from the ground in a shockwave around the druid as storm clouds erupt from a point in the sky over the druid's head. Spreading out 50 feet. Movement within the effect of the spell requires a DC 15 dex check to move. All creatures inside the spell take 4/d8 cold damage and must make a constitution save, DC = spell DC + caster constitution modifier. Frost begins to coat the creature's skin and clothes on a failed save, giving a disadvantage on all skill checks and dexterity checks. They can no longer take the dash action. The castor is automatically affected by this save.

Round 2. The area affected by the spell expands another 50 feet in radius. The area within the spell is now considered lightly obscured (+2 stealth), and snow, sleet, rain, & shards of ice combined with swirling 55 MPH winds give a disadvantage on all ranged attacks. Speed inside the spell's area of effect is halved. All creatures starting their turn inside the storm take 2/d6 bludgeoning damage, and all objects that are not on another creature are immediately frosted over. Temperatures drop to -25 degrees celsius and all fire, magical or otherwise, is frozen over within the spell's radius. All creatures reduced to 0 hp in the storm are frozen over with frost. All previous effects still apply.

Round 3. The area of the spell expands another 50 feet in radius. Spell's area is now considered heavily obscured (+5 stealth), and ranged attacks are now impossible. Flying in the spell's area is now impossible, the area is now considered difficult terrain. All creatures within the spell besides the castor are considered blind, DC 15 survival check to not be confused. All creatures in the area of the spell must make a DC 12 Wisdom save, on a failed save they are affected as if by the spell Sleep cast at level 3 as a hibernation effect from natural function. Creatures that are immune to sleep are considered paralyzed from the cold on a failed save. All Previous effects apply.

Round 4. The area of the spell expands another 50 feet in radius. All Previous effects apply.

Effect on the castor: Winter's Harbriner has a severe effect on the castor, its power coming at a steep price. While the spell is in effect, the castor takes 2/d8 cold damage from the spell at the beginning of their turn. They are considered to have automatically failed the Constitution save and are affected by the frost that begins coating their skin, giving a disadvantage on all skill checks. The castor also gets +1 AC from the ice coating their skin, and if reduced to 0 hp the castor is frozen over in frost. The castor is also affected by the DC 12 Wisdom save for hibernation, DC 15 acrobatics check to move, and DC 15 Survival check to be confused.

If the castor is killed, the spell begins progression in the reverse order from what is listed. If the spell was active for more than 4 rounds, take the total number of rounds it was active above round four and divide by 2. The spell only begins shrinking in intensity and size after this many turns have passed. The spell ends instantly if it is canceled by the captor. Permafrost and over-freezing remain after the spell ends.