Most accounts have no sight in them at all, only the swell. It begins as unease without a cause, then a weight behind the breastbone, then a throb in the teeth and the soles of the feet, slow and even, like a great bell struck far below the ground. Water in a cup trembles in rings; dust walks on a table. Those who say they saw one at the end speak of a darkness that was larger than the room it stood in, or of the room itself seeming to lean inwards and breathe. No two agree, and no smell or warmth goes with it.

They live in the Dissonance, where the beat is slowest and the copy of the world is lowest and darkest, and seem to follow its swell from region to region. On the surface they are met where the Dissonance presses close: in off-key places, and at the rare door that stands open for a moment by chance.

A Deepswell does not hunt by sight or scent. It is drawn to whatever sounds most like the world it copies, a lit house, a beating heart, a held breath, and swells towards it. Whether it means harm or simply cannot come near anything without crushing it is not known. It does not hurry. Survivors say it was the slowness that broke them: the pressure rose for a long time, and nothing in them could make it stop.

Its approach is felt through walls and through earth. Animals feel it first: dogs go under beds, horses refuse a road, birds leave a wood all at once. People already off their own pitch, the grieving, the fevered, the sleepless, feel it sooner and are drawn towards it rather than away. Close by, the swell sets loose stones walking, cracks old mortar, and stops the breath in a sleeper’s chest. What it does to those it reaches is not known; they are not found.

It gives nothing. A hamlet where one has come through is left with the dread and little else: a road animals still will not take, a house no one will sleep in, a low ache that comes back on certain nights. Running helps only if the runner is faster than the swell, and weapons and fire do nothing. What holds it off is the true note held against it: names spoken aloud, a bell rung in tune, a song sung true and steady while the pressure rises. Those who came back say the swell faltered when the singing held, and rose again whenever a voice broke.

In hill country it is called the low thing or the deep breath; some old holds speak of the ground’s heartbeat as an omen, and keep a tuned bell by the door for it. Folk belief holds that a Deepswell is the grief of the drowned or the buried, come up to be heard. Others say it is the Dissonance itself, leaning on the world. Neither is known; that Deepswells are born of the reflection is all the few who know more will say.