I have never made a race before, so this is my first crack at it. I imagined this race of Volcano People called Vulkaans. I guess what pops in my brain is the Vex build from Destiny, but more organic. They live in lava similar to how Tritons live in water. They are made of incredibly hard rock, and their skin is rock-like with jagged protrusions similar to fins of something like Merfolk. The males have large rock crests on their heads.
I won't go too much more into the background of all of it. Just help me balance this race out please. Is this balanced?
Ability Score Increase. Your Constitution score increases by 2 and Strength score by 1.
Age. Vulkaans reach maturity around the age of 100 and can live to be 800 years old.
Alignment. The Vulkaan societies keep to hard military regimens. However, Vulkaans also try to stay out of squabbles of other races. Most Vulkaans are Lawful Neutral.
Size. Your size is Large. Most Vulkaans stand between 7 and 8 feet tall and can weigh well over 250 pounds due to their rocky exterior.
Speed. Your base walking speed is 35 feet and a swimming speed of 20 feet.
Lava Origin. Due to the fact your people live under lava, you have a resistance to fire damage. However for the same reason you are vulnerable to cold damage.
Infravision. You have infravision out to 60 feet. You can see creatures and objects in this range that are Warm or hotter or Cold or colder as if it is illuminated dim light; you can see creatures and objects in this range that are Hot in a Cold or colder environment, and Frigid in a Warm or hotter environment, as if illuminated by bright light. You can't discern color, only shades of grey. You have advantage on Wisdom (Perception) checks to detect creatures who are Warm or hotter in a Cold or colder environment, and Cold or colder in a Warm or hotter environment. Your infravision is blocked by 1 foot of water, ice, or snow, and by 5 feet of water-based fog.
Rock Skin. Vulkaans have a jagged rocky exterior to protect themselves. You gain no benefit from wearing armor, but if you are using a shield, you apply its bonus as normal. When you aren’t wearing armor, your AC is 12 + your Dexterity modifier. After spending a full day out of lava, you add your proficiency bonus to your AC as the rock hardens.
Languages. You can speak, read, and write Common and Primordial.
I know Infravision is an odd one, but I wanted it to make sense thematically as to how they can see under lava. And I tried to model Rock Skin to be similar to Warforged, but nerfed a hair and with a different element to it as well.