Drawbridge
The drawbridge is a dungeon feature that occurs in NetHack. The Castle's entrance is a drawbridge, and two more are guaranteed on the Valkyrie quest. They are widely considered extremely dangerous; however, their threat can easily be managed by a knowledgeable player. Indeed, with a little caution the drawbridge can be a valuable tool.
A closed drawbridge is represented by #, and an open one is represented by ..
Destruction
If a drawbridge is hit by a force bolt (from the spell or a wand of striking) then it is destroyed. Any non-phasing monster in either the "open" square or the "closed" square (the portcullis or the moat) is very likely to die. A player's chance of being killed is not affected by hit points or armor class. However, flying or levitating increases chance of survival.
As of NetHack 3.6.0, iron chains are scattered from the drawbridge's destruction, and they can still hit you outside of those two squares. However, only those squares are considered potentially lethal.[1][2]
Once destroyed, a drawbridge can never be recreated. Casting a spell of wizard lock or zapping a wand of locking at the portcullis square creates an ordinary door.
Castle
The castle drawbridge can be opened by playing the passtune on a musical instrument. The passtune can be given to you by your god while praying on an altar or deduced by playing a game of musical mastermind in front of the drawbridge (gears = right note, right position; tumblers = right note, wrong position). Obviously, the sound option (acoustics in NetHack 3.6.0) must be enabled.
In NetHack 3.4.3 and variants, manipulating the drawbridge in this way did not advance the turn-counter (bug C343-318). This has been fixed in NetHack 3.6.0.
The drawbridge can also be opened by a wand of opening, spell of knock, or the blessed Bell of Opening, and can also be closed by a wand of locking or spell of wizard lock.
When a drawbridge closes, monsters (or the player) standing on it or the square it closes onto (the portcullis) will be crushed and killed and their possessions destroyed. Phasing monsters always survive (unless there are phasing monsters on both squares, leaving one with nowhere to go). Flying or levitating victims have a chance of surviving, significantly lessened if on the portcullis[3]—just keep trying. When a drawbridge opens, the same applies to monsters caught under it.
Killing a peaceful monster with a drawbridge has a 50% chance of decrementing your Luck because it does not anger the victim first.
Strategy
Once you have the passtune, the drawbridge can be opened and closed instantly (and at will) by playing the instrument again. Anything standing on the moat or portcullis squares will be killed, and you will even gain experience for the kill. If a flying monster survives you can just try again, taking zero game time. This is a fairly safe way of clearing out the hordes of monsters in the castle courtyard. Do note however that this will destroy any possessions carried by the monsters you crush. (Also, this advice applies only to vanilla NetHack 3.4.3; the fact that it takes no time is a bug (C343-318) that is fixed in most NetHack variants.)
If you stand in a line with the drawbridge and the castle fountain then soldiers inside may try to zap you with wands of striking, destroying the drawbridge. For this reason you should stand a knight's move away from the drawbridge when using it to crush the inhabitants.
Exercise caution when crossing the drawbridge. You never know when a monster with a wand of striking may be lurking. Some players prefer to destroy the bridge when they're done crushing things. Alternatively, jumping (other than the Knight's innate L-jump) can take you through the danger zone in a single move, leaving no time for monsters to destroy the drawbridge under you. Player deaths from the drawbridge are relatively rare, but are particularly feared nonetheless. Likely this is because it is the only non-delayed instadeath for which the immediate cause is outside the player's direct control (a monster zapping a wand of striking), and for which no common resistance provides any protection.
Valkyrie quest
The drawbridges in the Valkyrie quest cannot be opened or closed with a passtune, though they also may be generated raised as of NetHack 3.6.2. The usual methods still work: a wand of locking or wizard lock spell will close them, while a wand of opening, knock spell, or the Bell of Opening will open them. They are subject to being destroyed by force bolts, with the same risk of instadeath as the Castle drawbridge.
Fort Ludios
The door beyond the moat of Fort Ludios is not a drawbridge, but an ordinary door with a moat in front of it.
UnNetHack
UnNetHack includes drawbridges in additional levels, such as some Fort Ludios variants, Baalzebub's Lair, and inside Moloch's Sanctum. As with the valkyrie quest, the Castle passtune does not work on these drawbridges.
If a huge monster is blocking the drawbridge, it cannot be closed.[5] Additionally, there is a 1/5 chance of the mechanism being "stuck" and not closing per attempt.[6] Both changes are intended to make it harder to use the drawbridge to kill a large number of monsters in quick succession.
Reference
This page may need to be updated for the current version of NetHack.
It may contain text specific to NetHack 3.6.4. Information on this page may be out of date.
Editors: After reviewing this page and making necessary edits, please change the {{nethack-364}} tag to the current version's tag or {{noversion}} as appropriate.
