Homebrew
Mountain Born. Due to the icy peaks that make up a large amount of Jötunheim, the Jötnar are well adapted to such conditions. You have resistance to cold damage. You’re also acclimated to high altitude, including elevations above 20,000 feet.
Of Ice and Stone. The Jötnar have a strong connection to the base elements of ice and earth. This connection affords them minor control over these elements. You know the Mold Earth cantrip and can cast it on ice and snow too. The first effect of the cantrip works on snow but not ice. This cantrip does not count against your total number of known cantrips.
Icy Epidermis. Jötnar have a thin layer of an ice-like substance covering their skin, occasionally giving them minor protection from incoming damage. When you take damage, you can use your reaction to roll a d12. Add your Constitution modifier to the number rolled and reduce the damage by that total. You can use this trait a number of times equal to your proficiency bonus, and you regain all expended uses when you finish a long rest.
Eyes of Jötunheim. Jötunheim is a realm of many temperaments in terms of weather, causing the Jötnar to adapt to such conditions quickly. You can see through lightly obscured areas as if they were not obscured and through heavily obscured areas as if they were lightly obscured as long as the obscurement is caused by natural phenomena such as foliage, heavy rain, falling snow, mist, and other natural phenomena.