Living Metal

Living metal was first invented in the year 4617NA by the College of Arcane Metallurgy. It was a groundbreaking discovery said to have been made by accident by one metallurgist who was experimenting with the malleability of mercury and accidentally misspelled, causing a frightening explosion of unpredictable magical energies. The end result was fascinating, though not immediately well understood until nearly half a century later.
In simple terms living metal is a large number of microbial machines created through incredibly delicate magic that behave in a similar way to a virus. Non-living, non-sentient, yet still moving and replicating itself through the slow consumption of matter. It can be given new directives magically by the one who made it, allowing it to instead be used to transfer information, self-repair constructs composed of it, and even perform specific spells it has been told to perform. Living metal is a miracle that allows non-living metallic objects to generate their own presence in the astral realm. Even experience base emotions, though without a true conscienceless of their own.
At first it was used to make truly exceptional magical weapons. Swords primarily. Swords enchanted with spells of elemental power that could be wielded by mundane folk as if they had magic of their own, something enchantments couldn’t do prior. In the hands of a skilled mage however they provided a second source of spellwork, allowing the wizard to hold a spell in their mind while flinging another from the sword in their hand, giving them an enormous advantage over an unnarmed sorcerer.
It wasn’t long after that though that living metal and its many possibilities were discovered. Now it is used in all sorts of automatons and complex, near-thinking machines. Every mechanical man or machine servant in the world is built upon a delicate foundation of interwoven living metal systems that keep the automaton moving and allow for a far greater range of possible responses than ever before. Some automatons are even capable of mimicking human behavior to an alarming degree, though none yet have proven to be truly self aware enough to be considered sapient.