Dark is an element like fire or water, no more sinister in itself than a moonless night. A dark-shaper channels emotion through Vulus, the darkness layer of the Elemental Planes, and works shadow as a substance. They deepen it, pool it where there was none, swallow a lantern's glow, blind a room that stood lit a breath before. Shadow is a thing here, not a hole where light should be. The dark a shaper calls up has weight and edges and stays where it is put, and the element answers the way stone answers an earth-shaper, with no will of its own.
In this it is the plain opposite of void. A void-shaper takes presence out of a space; a dark-shaper puts a presence into one. Light and dark are both presences, the one a radiance laid over the world and the other a shadow-stuff with body to it. Void alone is the absence, and the three are easy to confuse only by people who have watched none of them worked.
The feeling that feeds dark is the feeling people keep hidden. Fear, shame, a secret held close, a grief told to no one: Vulus answers what is withheld and kept out of sight. A shaper reaching for it out of bright open conviction will find the layer all but deaf to him. The element wants what is concealed, and that shapes who turns out to be any good at it.
What gets dark-shapers killed is what people assume they are doing. Two other things in Alaria wear the word dark, and dark-Kethic is neither. Necromancy is Deoric work, the severing of a person's malstaric thread through the Nethereal overlay, and it costs the caster life to perform. The shadow-energy of Malstaris is the native power of an entire plane, the dark place beneath the Wastes, not a source any Kethic caster reaches. Dark-Kethic is only the element, shadow drawn through Vulus and nothing more, and it renews at the scale any living shaper works it. The line is clean in the cosmology and hopelessly muddy in a frightened town, where a man who can put out the candles is a man who keeps company with the dead.
So the danger in dark-work is rarely the element. It is the rope. The practice is taught behind shut doors and worked quietly, in the deep mining reaches where the dark is already total and among the night-trades that prefer not to be watched. The other hazard is plainer and more immediate. A shaper who floods a room with dark blinds himself as fast as his enemy, and a thing hidden in that black can be lost to the one who hid it as easily as to anyone hunting it. The ones who last in the trade are the ones who learned to fight and keep their bearings in a dark they made and cannot see through either. Pushed past a shaper's own capacity on a strong seam, dark-work can tear the seam itself: Shadowkeep in northern Shyona is the standing example, where a dark-shaper of rare depth drew more shadow through a Vulus seam than it could give without rupturing, and the keep and its grounds have lain under a shadow the noon sun does not lift ever since. Mastery comes by the three axes laid out under Kethic, control and a deepened channel and a teacher who can drill the craft but never gift the attunement, learned here behind closed doors by people who would rather not be watched learning anything.