What It Does
The line's signature — the dark, held where the hand says, and the absence is the whole argument, and the one who cast it is the one who gave the blood. It is the dark school's answer to the light school's dawn rite: the dark does not reveal, the dark keeps the oath in the absence, and the absence is the one who holds the line.
The Cost
Circle 5 · Dark · Exchange: blood — casting time three rounds. On the ladder in The Veil, the blood rung is the price.
The Failure
The oath is let go shaped, and the shape is not the one the hand sent — the dark is the one who keeps, and the one who is kept is the one the story is about.
In Stories
The archmage's dark spell; the one the camp does not cast twice, because the dark remembers the name.
The door's scale anchor is Shadowveil — the dragon casts it without thinking, which is how a reader learns the shape of the thing.