What is drucraft? It is the art and skill of working with essentia.
Essentia is fundamental and omnipresent, a universal energy source that only interacts with the physical world in limited ways. It can occupy the same space as material things, and when doing so takes on some of their characteristics. It ebbs and flows, following invisible currents like those in the ocean or sky, changing as it moves. From time to time these currents will converge, following the shape of the land to form a location called a Well. The essentia that accumulates in a Well is still mutable, but is inclined towards a certain aspect of reality.
In its raw form, essentia is almost completely inaccessible to living beings. A living creature spends every moment of its life surrounded by essentia; it is in the air they breathe and the food they consume; it suffuses their bodies both in waking and in sleep. But it is no more accessible to them than the chemical energy locked away within a piece of rock. A thundering waterfall may contain more power than a hundred men, but not one of them can simply thrust an arm into the water and take it. The water rushes on, oblivious to their desires, and it will continue to fall long after they and their descendants are gone.
But with the right tools and the knowledge of how to use them, that power can be harnessed. A water turbine draws upon the power of a waterfall, siphoning off its energy to generate electricity. In the same way, through millennia of work and research, practitioners of drucraft have developed techniques to draw upon the power of essentia. In the case of drucraft, the tool that makes it work is the sigl.
A sigl is a tiny piece of crystallised essentia, created when a drucrafter of sufficient skill draws upon the reserves of a Well and converts them into physical matter. Sigls have the power to conduct essentia, transforming its raw potential into a specific effect. They are single-purpose tools, locked at their moment of creation to both their maker and to the effect they were designed to produce.
Sigls are durable, but not eternal. Essentia resists being given physical form, and when so transformed, it eventually returns to its natural state. The process is slow, often taking hundreds or thousands of years, but is also inevitable. Gradually the sigl sublimates, transforming bit by bit into free essentia, which drifts away. This essentia is reabsorbed into the currents flowing across the land, and the cycle begins anew.