Accustomed to life underground, you have superior vision in dark and dim conditions. You can see in dim light within 60 feet of you as if it were bright light, and in darkness as if it were dim light. You can’t discern color in darkness, only shades of grey.
You have advantage on saving throws against poison, and you have resistance against poison damage.
Whenever you make an Intelligence (History) check related to the origin of stonework, you are considered proficient in the History skill and add double your proficiency bonus to the check, instead of your normal proficiency bonus.
The mountain dwarf can pinpoint, by scent, the location of ferrous metal within 30 feet of it.
A mountain dwarf can detect and pinpoint the origin of vibrations within a specific radius, provided that the monster and the source of the vibrations are in contact with the same ground or substance. Tremorsense can't be used to detect flying or incorporeal creatures.
A mountain dwarf can prefectly recall any path it has travelled.
You gain proficiency with mason's tools.
You have proficiency with the battleaxe, handaxe, throwing hammer and warhammer.