Elemental Endurance

Either through intense training or some natural gift, your body is resistant to extreme temperatures and gain the following benefits:

• Increase your Constitution score by 1, to a maximum of 20.
• You are unharmed by temperatures as low as −50 degrees Fahrenheit and as high as 140 degrees Fahrenheit. 
• When you take fire or cold 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. After you use this trait, you can’t use it again until you finish a short or long rest.