Pacifying levels refers to stopping further monster generation by allowing a section of the level to fill up with bred monsters, until the level stops generating new ones. The magic number appears to be 40 — once there are forty monsters on a level, no new ones will be spontaneously generated — although breeders and summoners will still produce monsters as long as they have access to open space.

In ADOM 1.2.0 prerelease 23, 40 monsters was not observed to be enough to pacify a level. Monster generation did not stop until 80 monsters were present. In release 60, 105 monsters was not enough to pacify the Big Room but 195 was; the new number is unknown (120 or 160 are possible)


For the same reason that many players pacify the Big Room: to allow herbs to be harvested peacefully. But it's generally much easier to pacify other levels, so as long as another herb-growing level can be found, it's not necessary to spend the extra time to pacify the Big Room.

A successfully pacified level also makes an excellent storage area, especially if a coaligned altar is located within for easy detection of B/U/C status and creation of holy water.


On regular levels, this is as simple as finding a big enough room, or a pair of smaller rooms connected by a corridor, or digging out a smaller room until there are at least forty floor tiles, and then leading a breeder there. Run or teleport away and close the door. Since worms, insects, jellies, and the like can't open doors, it may not be strictly necessary to lock them up, although a closed door may potentially be opened up by another passing monster before the level is pacified. Relatedly, on deeper levels or with higher-level PCs, a monster capable of smashing locked doors (such as a hill giant) may spawn inside the room. Therefore it may be a good idea to stay by the door with a wand of door creation until monster generation stops completely. It may also be necessary to enter the enclosure to kill non-breeder monsters in the event that they block a corridor.

It appears that, at least on regular (non-cavernous) levels, monster generation slows significantly when the level has only a fraction of the forty monsters needed to stop it completely, and since the growth rate of breeders is exponential, it takes only a short time once a breeder is found before the rest of the level is completely peaceful, and more herbs can be planted.


According to the ADOM Guidebook, the following are breeders:

Note that other insects (like fire beetles) are not breeders, nor are other jellies (like gelatinous cubes, gibbering mouthers, yellow oozes, death oozes, and stone oozes). The monster symbol doesn't necessarily tell you whether it will breed, although all of the worms (represented by "w") do.

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