Abyssal Blizzard

Any creature with the mark of Sithhud that enters the blizzard gains the glacial armor effect until the armor breaks or is applied again. Any creature that does not bear the mark of Sithhud suffers a –2 penalty to Dexterity, a –1 penalty on attack rolls, has its speed reduced by 5 feet, and takes 1d6 cold damage each round. Additionally, the creature must pass a concentration check (DC = 15 + the spell's level) each time they cast a spell.