In the north, some Biomechanical born under the influence of the Furnace exhibit a greater degree of deviation and are thus given the epithet "Forged."
Their charred skin is cracked all over, revealing glowing, red-hot muscles like solidified lava covered in volcanic ash. It's hard to say whether the magma's heat changed them, or if this is their original form.
Forged Diggers differ from their eastern counterparts in that they can endure extremely high temperatures. They hide in magma to ambush their enemies, inflicting great losses upon the cave explorers of the north.