While the creation of both simple and complex objects through various methods and out of various materials is encompassed within the Craft Ability, Creation is a complex place. Beneath the mundane exists a complex system of essence and mote, metaphysics and theology, and understanding these things takes a far different array of skills than those needed to create objects, while understanding the systems beneath provides no skills for creating things from that knowledge.
The most advanced forms of crafting thus occur not within the aegis of a narrow skillset or a single Ability, but through the synergy and synthesis of several, almost invariably coming together with the willfull and visionary mindset of a sorcerer, together allow a craftsperson to achieve greater heights than any one would have allowed on its own. This complex type of crafting was at its zenith during the Golden Age, when the Solar Exalted forged fantastic wonders even as they debated the underlying truths of existence... in the Age of Sorrows, much has been lost, but even now their legacy can still be seen in shining wonders left behind.
For each type of esoteric crafting, a trait can be derived based on several Abilities. In order to use an esoteric craft (such as to evaluate an appropriate mechanism or in Artifact Creation), this trait would be rolled where a mundane craftsperson would use a Craft (Ability). For purposes of performing maintenance, or serving as an assistant to a craftsperson, there is some leeway... working as a team, several individuals can contribute one or more of their Ability ratings to determining a common Crafting Trait. This requires at least some training and discipline within the team, and is most commonly seen amongst thaumaturge-technicians in the Realm's Imperial Legions and in Lookshy.
Due to their difficulty and complexity, the esoteric crafting disciplines can access great powers compared to more 'mundane' artifice, and their focus often makes their use of Exotic Components in Artifact Creation more predictable, advantageous during the infrastructure-rich days of the Golden Age. However, the very complexity of these works often required additional attention, and when the Wyld-shaping powers of the Solar Exalted were lost the severity of this increased, many such works requiring Maintenance and Repair.
Magitech Crafting is, at its core, the engineering of Essence. Sources which generate motonic energies must be identified, systems forged to conduct Motes from one place to another, to shape them to the needed form and intensity. Principles of mundane and thaumaturgical craft can be applied directly, lenses can focus essence just as they can vision, turning clockwork can pass on motonic motion just as they can physical. Though far from widely known, magitech is perhaps the most prevalent of the esoteric crafting approaches in Creation today, with several schools and societies still attempting to maintain the wealth of Category:Magitech left over from the First Age. Magitech is most closely linked to the sorceries of the Devonian and Kinetropic Schools.
Necrosurgery Crafting is the science and engineering of reanimating the dead. To the necrosurgeon, the body is a vessel, animated by the energy of life, and perhaps a soul. The soul is immutable and irrestorable, ressurection impossible, but the necrosurgeon observes that life force is a different matter... at death, the life energy vanishes, leaving behind a spent vessel... one that can be reactivated, if only a new energy source can be forced into it. As dead flesh is far more malleable and accepting of modification than living, the necrosurgeon can take advantage of the corpse's inert state between power sources to make augmentations, the new better than the old.
Necrosurgery is most often linked with the necromancy of the Shizuan School, and while it is very rare in Creation it is practiced and taught widely in the Underword, where it serves to forge the armies of the monstrous Deathlords.
Biogenesis Crafting is the crafting of living things. At its most basic, it can be seen to have evolved from the same base as animal husbandry, or the nomad shaman's knowledge of which fruiting plant will likely provide best bounty in the coming year. It studies the living body, along with the life force that drives it and the essence and traits within it in order to determine how these will be passed on to offspring, how these might be augmented, and even how whole new bodies and life forces might be forged. Once, practiced with great respect for the natural state of Creation, it was commonly associated with the Salinan School of sorcery, but this is exceedingly rare in the Age of Sorrows. The most common practice of this type of crafting can be seen amongst the ranks of the Realm's Scarlet Dynasty, who more often apply the sorcerous principles of the Kinetropic or Silurian Schools to biogenesis in order to produce new beasts to serve their peasants, or to direct their Dragonblooded Breeding programs.
Microtheurgy Crafting is an approach to crafting based not on a search for underlying principles but on a replication of an already-working concept: the gods of Creation and their Celestial Bureaucracy. In Creation all things have a god, and the system existing between these gods serves to keep the whole functional, defends an island of stability within the formless Wyld. While awakening the god of an object has long been understood as useful in artifice, microtheurgical artifacts instead seek to replicate whole systems of divinities on a minuscule scale, forming pantheons of Nanogod spirits empowered by worship to accomplish the function of the device, just as Sol Invictus is empowered to be unconquered defender of Creation. Many of the most advanced artifacts of the Golden Age were based on microtheurgy, and it was most closely associated with the sorceries of the Archaic School.