At every nightfall the game draws one of these six at random, and it lasts until dawn. The notice top left names it. Each entry says what it does in the current version.
Fen-mistSight is short till dawn.
Sight falls to 3 tiles until dawn, against 5 on an ordinary night and 9 by day, so less of the fen is revealed and raiders are seen later.
A still nightNothing crawls out till dawn.
A wave that comes due during this night sends nobody; raiders already on the fen keep coming. It still counts toward Held the Line.
Bale-fireA Sundered Place wakes early.
The first sleeping Sundered Place in the fen's list wakes at once, so the next waves come from one more lair. It cannot happen on the first night.
Drowned lightsA ruin-cache shows on your map.
The next ruin-cache your people will dig is revealed on the map with the ground six tiles around it. Nothing shows once all five are dug.
Rot-bloomA food patch has spoiled.
One patch of game cover, the first in the fen counting from the top-left corner, turns to bare dry land with nothing left to hunt.
Quiet waterThe eels run; fishing doubles till dawn.
Every load of fish a fisher brings home that night counts double. It lasts until dawn.