So far along the lines of this matter, I've decided that if they were 5'8" and humanoid, composed of something similar to Tungsten, so they don't melt or burn, they would weigh around 3,846lbs/1,744.5kgs, which seems unlikely for a generally humanoid form to support. Assuming they have extremely efficient (for strength and endurance) muscles and are capable of supporting that mass, could they even venture outside a volcano without crushing or sinking into the ground beneath them?
If we say their skin and bodily processes can be sustained by an odd diet between carnivore and ingesting lava rocks, is it possible for them to have a body temp around a "low" 120 degrees Celsius?
Suppose they went into the ocean at some point, is biological insulation capable of supporting cold and hot extremes alike? Been trying to make this character with as little magic as possible, but there's already a psion, so it's not off the board completely.
Creature could also potentially have scales, but would it be even stronger than the metal-like flesh? Or some sort of aid to insulation?