Nighttime barter
Natural witches originate at isolated cottages. They return home by day and act outdoors at night. Right-click a calm grounded witch at night to barter. Angry, flying or occupied witches refuse, and daytime trading is refused. Prices are marked up and stock is finite.
Attacking can provoke poison and broom escape. Milk clears poison even while fully fed/hydrated; herbal remedies are another treatment route. Do not assume town guards welcome independent witches.
One shell per witch per night
Collect seashells from shore clusters or crabs. At night, select one and right-click the witch. The first accepted shell that night is consumed in finite play. Usually it returns a forest mushroom; a one-in-twenty-four roll gives a Twilight crystal instead. Further same-night shells stay with you, and daytime attempts are refused.
The current exchange explicitly clears the witch's guest state. Older release notes saying a shell grants cottage hospitality are superseded for this interaction.
Twilight protection
Put an active Twilight crystal in your offhand with F. It protects against the hostile night marine encounter and can cancel a siren hold. It expires at dawn, becoming its spent form even when stored or dropped; a chest does not preserve it.
The old item name was Nightveil. The current name is Twilight crystal, with its numeric identity retained for compatibility. It also suppresses the ordinary hostile-mob attack/theft event paths and eligible enemy projectiles. It is not universal invulnerability: environmental hazards and special contact-damage systems have their own rules.
Settlement consequences and retired specimens
Guards can apprehend a witch entering their community and use the ordinary cell/nighttime trial system. Releasing a captive can make the settlement hostile. A witch is an independent expensive trader, not an ordinary civilian invitation source.
Monster specimens are retired from current library availability, fresh witch stock, chemistry and raider exchanges. A compatibility name/ID remaining in an old save does not establish a current specimen-farming loop.