race features:
Stone’s Endurance: You can focus yourself to occasionally shrug off injury. 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. After you use this trait, you can’t use it again until you finish a short or long rest.
Mountain Born: You’re acclimated to high altitude, including elevations above 20,000 feet. You’re also naturally adapted to cold climates, as described in chapter 5 of the Dungeon Master’s Guide.