Vaults, also sometimes called the Magic Memory Vaults, are 2 by 2 sealed rooms that are randomly generated in the Dungeons of Doom. They contain gold in all four squares, in an amount reflective of the dungeon level. The Big Room and the Rogue level never contain any vaults. Otherwise, they have a 50% chance of being generated on any level that has at least 6 rooms. However, there is not always room for a vault, so in practice this number is even lower.
Finding and getting into vaults
The following messages tell you there is a vault on the current level:
- You hear the footsteps of a guard on patrol.
- You hear someone counting money. (Vault not raided)
- You hear someone searching. (Vault raided and empty)
There is 67% chance it can be accessed through a closet that contains a teleporter, recognized by the engraving "ad aerarium" (Latin for to the vault) in the dust in front of it. If you do not find the closet, you may want to read a scroll of magic mapping or a scroll of gold detection, or quaff a potion of object detection and dig or teleport in using some other method. You may also just dig around randomly watching for areas where a vault would fit. Remember that the vault is actually 4 by 4 squares because the walls also take some space.
On deeper levels, the "ad aerarium" engraving may indicate a closet with a level teleporter instead. This does not mean that there is no Vault teleporter on the level; it is possible for both the Vault teleporter and a level teleporter to be generated on the same level.
Sometimes, monsters will be generated inside vaults or teleport into vaults. You can detect them by using Telepathy. It is also possible to fall into a vault from a higher dungeon level, perhaps by stepping on a trap door. When you are randomly placed on the new level, you may end up inside the vault.
If there is a dwarf wandering around on a vault level, he may find the vault and loot it in the course of his own explorations, leaving behind a tunnel connecting the vault to the rest of the level. Beware! If the guard arrives while you are in the empty vault, he will neither know nor care that the dwarf, and not you, did the looting. So don't linger: find that dwarf and take his gold. Digging monsters such as rock moles or umber hulks may also open a path to vaults.
Looting a vault
The simplest way to loot a vault is to dig a path in, collect the gold, and leave promptly. When in the vault, you only have a short time to get the money and be gone. If you stay in the vault for too long, a guard will appear, and you will need to deal with him. If you are unable to speak, (due to wearing an amulet of strangulation, being polymorphed into a silent monster, mimicking an object, paralysis, etc) the guard will leave, saying that he'll be back when you're ready to speak with him. Note that he doesn't return the instant you become ready, but at some near time in the future; It is entirely possible to wake up when he's still away, thus avoiding him. Otherwise, the guard will inquire your name, saying, "Hello stranger, who are you?". Giving your name as "Croesus" (or "Kroisos", or "Creosote") to the guard gets rid of him if you haven't killed Croesus already (if you have, the guard will become angry instead ), but lying carries a small alignment penalty for lawfuls (of course, if your name is actually Croesus, Kroisos, or Creosote, you are not lying and there is no penalty). Note that this potentially leaves you trapped in the vault, if you cannot dig or teleport out.
If you give any other name, the guard will demand that you drop all of your money (including money you already had, and any money in containers) and follow him out of the vault. If you fail to drop the gold quickly enough the guard attacks, but once you have dropped the gold, you can take your time following him. If there is no path to the vault, when the guard leads you out of the vault, a temporary exit corridor is created that will disappear when you reach an open square. If you take another path out (perhaps you dug into the left side of the vault, and the guard built a temporary path on the right, and you left via your path instead of his), the guard will stay in the vault. In any case the guard will magically repair any damage to the vault walls as soon as you leave, and the guard will also prevent you from digging in the vault walls while he is present. To get the guard to leave, you need to leave with him. If necessary, this can be done by digging your way back to the guard's temporary path to rejoin him, so that you can leave together.
In NetHack 3.4.3 and prior versions, it is possible to steal from a still-closed vault using a pet. First, you must have both the pet and yourself in the vault. This can be done by blocking the pet on the doorway to the vault teleporter closet (it can't leave the doorway diagonally); the pet will eventually take the teleporter (even if it is aware of the trap). A pet using the teleport trap will not use it up, and then you can take the teleporter. Alternately, get into the vault by any means and then call the pet with a magic whistle. Once you are in the vault with your pet, pick up all the money and then drop it in one stack (along with your own). Wait for the guard, give it your real name (unless you are Croesus or an equivalent, in which case give a false name to prevent being trapped in the vault), and then follow it out a couple of steps. Follow it as slowly as you must, making sure your pet follows and brings the money with it; if you exit the guard's temporary path while the pet is still inside, it will become trapped in the reformed rock. In NetHack 3.6.0, pets will only pick up a single gold piece at a time, making this strategy useless.
Getting out of a vault
If you did not go out of the vault with a guard, you have few alternatives. You may dig yourself out by using a pick-axe or any other method or you may teleport out. If you have neither means to dig or to teleport, you will want to leave the gold and get out with the guard — you can always come back later and get the gold you left behind. Make sure you don't displace your pet into the guard's pathway when it closes! This will not kill it, but teleport it to elsewhere on the level and make it somewhat less tame.
Getting into Fort Ludios
A vault between level 11 and Medusa's Island may contain a magic portal that takes you to Fort Ludios. Each vault in that range has a 1/3 chance of containing the portal if it has not yet been generated in another vault (except the level with the portal to the Quest, which will never have the Ludios portal). In any given game, Fort Ludios may be inaccessible if the portal was not created. Attempting to teleport into a vault and being bounced out with a "Sorry..." message means you attempted to teleport onto the magic portal trap. In UnNetHack, Fort Ludios is more likely to be accessible - the portal is always in the first vault below level 10 (that isn't the Quest level). It is still possible for there to be no entrance to Ludios, but that requires the complete absence of vaults below level 10.