| Possibly constructed by some powerful madman, the Vaults are said to be home to great treasures. The blood spattered liberally around the entrance suggests that there is a certain amount of violence, too.
The Vaults are eight levels deep and contain the silver rune. The entrance can be found between levels 15 and 20 of the main dungeon.
|These stairs lead down into the Vaults, said to be home of great treasures. They are sprinkled with spots of blood.|
The Vaults are a convoluted 5-floor Dungeon branch filled with long, wide hallways and countless treasure chambers (most of which are unfortunately empty). They are guarded by a wide variety of late-game monsters, as well as a number of guards unique to the branch, but the promise of the silver rune of Zot, access to the Crypt and the Hall of Blades, and four guaranteed treasure or shop vaults makes it well worth the hazards. Stairs to the Vaults can be found between floors 15 and 20 of the Dungeon. 
The Vaults are a sprawling compound made up of wide hallways and small chambers of various shapes and sizes, most of which are separated by doors. Composed primarily of stone, metal, and green crystal walls, only the most powerful Earth Magic specialists or Lugonu followers can expect to alter the floor plan much. Because the arrangement of rooms can be extremely convoluted, it's easy to get cut off from the stairway back up if you aren't careful; try to clear rooms methodically to avoid enemies you missed showing up when you're already half dead.
The fifth and final floor changes this pattern abruptly. The floor contains four very large rectangular chambers that take up almost the entire area, except for a cross-shaped central hallway separating them all and an outer hallway bordering everything. All three normal staircases from the 4th to the 5th floor dump you in the very middle of the room, which will be surrounded by many vault guards and other angry Vault inhabitants. Fortunately, this floor also houses an immense amount of loot and possibly shops, and the silver rune of Zot.
The Vaults are inhabited by a wide variety of monsters (almost anything that can appear in the lowest floors of the Dungeon can generate here) with a very diverse array of attacks, but generally speaking the biggest threat is simply getting beaten to death by sheer brute force. Stone giants, yaktaur bands, and other creatures which can deal high physical damage output at range are common enough, and the wide hallways and open chambers make it difficult to effectively bottleneck opponents or cut off lines of fire. Pack enemies also appear in great numbers, ranging from high-level orc bands to devastating hell knight packs, and the various guard units unique to the Vaults each cause their own issues:
- Vault guard: Plentiful lumbering oafs in armour.
- Ironbrand convoker: Recalls and buffs enemy units from elsewhere on the floor.
- Ironheart preserver: Soaks partial damage for other enemies, effectively doubling their HP until the preserver dies.
- Vault sentinel: Wakes up nearby enemies, afflicts you with Sentinel's Mark, often has a crossbow.
- Vault warden: Can open or seal shut doors and stairs around you, forcing you to kill him to escape.
Bring sufficient firepower, take your time, and be ready to take a different staircase down if the one you just used places you in a fight you just don't want to deal with right away. Also, if you get hit with a Sentinel's Mark, retreat to an empty floor as quickly as possible. The reinforcements it will bring can be devastating on a mostly unexplored floor.
Do not go to Vaults:5 before you are ready for it. If you had difficulty with floors 1-4, floor 5 will probably be too much for you.
The fifth floor is an abrupt change from the first four. All of the standard down staircases to V:5 place you in the very center of the floor, with a ring of over a dozen vault guards waiting for you and several other (much more dangerous) opponents lurking right behind them. These monsters can include titans, storm dragons, quicksilver dragons, shadow dragons, and liches, along with the worst of what you've encountered in the top 4 floors. No matter what your character type may be, charging in and slugging it out is very likely to go poorly.
Melee characters may be tempted to stair dance to break up the enemy as much as possible. When this works correctly, you can usually get a small group of vault guards to follow you up, and you can safely deal with them on V:4. However, this is a dangerous practice due to the possibility of a vault warden generating within sight of the entry stairs. If he should seal the staircase back up, you'll be trapped on the floor until he's been disabled. Casters with powerful Storm or Bolt spells can usually take him out quickly, but that still leaves you subject to several attacks in the mean time. Casting Alistair's Intoxication with clarity works well here; you'll confuse the majority of the guards, causing them to injure each other and leaving you free to take out the more serious threats. This is still a poor strategy, however, as the noise you generate will wake and lure out monsters from the four treasure vaults.
Alternatively (and much less hazardously), you can enter, controlled teleport or blink your way out of the ring of guards, and then flee down one of the hallway while hasted. This will generate much less noise than a prolonged battle, and once you've cleared some distance and outrun your pursuers, you can take out your pursuers one by one. Once you've escaped pursuit, clear the outer hallway of the floor at your leisure before returning to the stairways. While a few dangerous opponents will likely be waiting along this border, this approach greatly reduces the odds of noisy combat waking up reinforcements, and by the time you circle your way back to the stairs up to V:4, you'll find them nearly unguarded. At that point, you may cautiously investigate the vaults.
When using the above technique, a scroll of immolation can be devastatingly effective for magic users. Read the scroll as your first action on the level. After blinking, and the horde is all to one side, keep casting cloud spells (poisonous cloud, freezing cloud, fireball) as you retreat down the hallway to start a cascading chain reaction of vault guard detonations. (rF+++ would be advised to prevent any accidental blowback.)
Resistances are much more important on V:5 than on the floors above. The draining attacks of shadow dragons can strip away your skill levels with frightening speed unless you have negative energy resistance (preferably rN+++). Failing that, high evasion and Repel Missiles helps tremendously. Storm dragon breath can be brutal as well without electricity resistance, which also protects against the lightning bolts of titans, but these also know Airstrike, so avoid flying in their presence. Quicksilver dragons deal severe damage regardless of your defenses, so try to make them a high priority. Packing some fire and cold resistance on top of everything else is advisable, as there are plenty of other dragon types around, not to mention casters with broad spell lists.
Using an uncontrolled teleport or heading down an escape hatch from V:4 to V:5 may place you in the safe outer hallway, but there's a better-than-even chance that you'll end up stuck in one of the four vaults. While it's not impossible to fight your way out, it's no easy task. Avoid uncontrolled teleports unless you've already explored most of the floor or it's your only option.
As the monsters here are significantly deadlier than those on the floors above, the warning about Sentinel's Mark goes double here. If it hits you, get back upstairs quickly.
In 0.14 it will be necessary to obtain a rune of Zot to enter this branch, and its entrance will be located on D:14-15. Also, the four chambers on Vault:5 will have entrances at each of their corners, not just in the center of the room.
Prior to 0.12, the Vaults were made up of 8 floors, the first 7 of which were all wide open areas spotted with rectangular rooms. Also, the vault guard was the only guard-type monster found here, and they usually appeared on the eighth floor.