Trap

Version 0.22: This article may not be up to date for the latest stable release of Crawl.

Traps (represented by ^) are Dungeon features that harm characters or monsters who step on them. They do not appear on the map until detected, except in some vaults. Most traps are magical in nature, but some vaults may also place mechanical ones.

Strategy

Your chance to detect traps depends on your experience level and the distance to the trap, and can be increased by worshiping Ashenzari, and decreased by the Blurry Vision mutation.

Flying players still trigger traps as normal.

Traps that fire ammunition have a limited supply of ammo.

Once you have detected a trap, you can (with thoughtful maneuvering) use it to harm or block monsters who are pursuing you. More intelligent monsters are much more likely to avoid them, however.

Trap Mechanics

Mechanical traps do not always go off when stepped on. The odds of setting one off are:

• For traps the player knows about:
  • 2 in 3 chance for blade and net traps.
  • 1 in 4 chance for all other traps.
• For traps the player does not know about:
  • Blade and net traps always go off.
  • 4 in 5 chance for all other traps.

For monsters, the odds are different:

• For traps the monster knows about:
  • 1 in 2 chance for blade and net traps.
  • All other traps always go off.
• For traps the monster does not know about:
  • 4 in 5 chance for blade traps.
  • 2 in 3 chance for net traps.
  • All other traps always go off.

If a mechanical trap is triggered, there is still a chance for the trap's weapon to miss, depending on your evasion and dexterity. The Repel Missiles and Deflect Missiles spells reduce the chance of a projectile hitting (except for the net trap, which drops the net rather than firing it). If you fail to evade the projectile, but are wearing a shield, you may instead block the projectile.

Monsters & Traps

Different monsters react differently to traps. Most monsters with animalistic intelligence or above will avoid ones they know about, and refuse to cross a trap even if there is no other way to reach you. Mindless monsters like zombies will walk through traps regardless of how much damage it might cause them. Zot traps are special: if you're in sight when a hostile monster walks into one, you get zapped. ("The power of Zot is invoked against you!")

In some situations, monsters already know the locations of traps:

• Monsters native to a dungeon branch (eg. orcs in the Orcish Mines) already know the locations of all traps in their branch, since they live there.
• Monsters friendly to the player, and good neutrals, know the location of all traps that you know about, since it's assumed that you would tell them about the traps.
• Monsters with high intelligence or greater have a 1 in 3 chance of knowing about the existence of any single trap.

Trap Types

Notes:

• Only teleport, shaft, alarm and Zot traps are placed randomly.
• Shaft traps won't be placed in corridors in the first 7 levels of the dungeon.
• The damage caused by mechanical traps is reduced by the player's AC.

Trap	Description	Amount of ammo	Base damage to player	Base damage to monsters	Trap type
Alarm trap	Makes a loud noise and afflicts you with the Sentinel's Mark status effect	N/A	None	None	Magical
Shaft	Opens a hole under the victim, sending them to a deeper dungeon level	N/A	None	None	Natural
Teleport trap	Teleports the victim to a random location on the level	N/A	None	None	Magical
Zot trap	Produces a powerful magical miscast effect	N/A	Varies by effect	Varies by effect; only affects friendly monsters	Magical
Arrow trap	Fires an arrow	3 - 11	1 - 15	1 - 7	Mechanical
Blade trap	Swings a huge swinging blade	N/A	48 - 76	10 - 38	Mechanical
Bolt trap	Fires a bolt	3 - 11	1 - 40	1 - 18	Mechanical
Needle trap	Fires a poisoned needle	3 - 11	None, but may poison	None, but may poison	Mechanical
Net trap	Drops a throwing net	1	None	None	Mechanical
Pressure plate	Causes something to happen, usually bad.	N/A	None	None	Mechanical
Spear trap	Fires a spear	2 - 7	1 - 26	1 - 10	Mechanical
Web	Induces the held status for several turns	May break after each use	None	None	Mechanical

Note that the "pressure plate" trap is a "software trap"; rather than a fixed result, its effects are defined by the vault it places as a part of, and might include stuff like dumping out a basket of spiders, or dropping a grating to block the path behind you.

Obsolete Traps

Over the years, many traps have been removed from the game for various reasons. These include:

• Shadow traps (Removed in 0.17)
• Gas traps (Removed in 0.13)
• Axe traps (Removed in 0.11)

Trap overhaul in 0.23

Version 0.23: This article may not be up to date for the latest stable release of Crawl.

In the upcoming version of Crawl 0.23, traps have been overhauled. The following is a description of how the new trap system in 0.23 will work.

• All traps will be revealed immediately when the player enters line of sight of the trap.
• Traps will not be triggered by monsters when the player is not in line of sight.
• Blade, bolt, needle and spear traps will be removed from the hall of Zot on Zot:5 and from Tomb, remaining only in the Ossuary.
• Alarm traps will cause a loud noise and inflict Sentinel's Mark on the player when stepped on by a monster in line of sight of the player.
• Net traps will net the player (with no chance to miss or block)) when stepped on by a monster in line of sight of the player.
• A new trap type will be added, called a dispersal trap, which will blink all players and monsters in line of sight of the trap when stepped on by anything. With lots of monsters around, this may disrupt the player's positioning and cause the player to become surrounded much more easily; when fighting an enemy alone however this may blink the monster away from you and give you time to escape upstairs without the monster following you. This trap will generate in some vaults, Tomb and the hall of Zot, as well as randomly generating in the dungeon alongside Zot, teleport, alarm and shaft traps.
• There will be a new mechanism for randomly trapping the player unexpectedly:
  • The player may randomly be trapped when exploring new tiles, instead of when stepping on new tiles that have an unseen trap on.
  • Trap effects triggered in this way will be either that of an alarm trap, a shaft, or a teleport effect that always places you near monsters.
  • The chance to be trapped through exploration on any given floor will be (1+absdepth/10)/9, where absdepth is a specific value representing the approximate depth of any floor in the dungeon from the dungeon entrance and the difficulty of that floor. For example, D:15 is absdepth 15, Lair:1 and Orc:1 are absdepth 11, Elf:1 and Swamp:1 are absdepth 16, Zot:1 is absdepth 27.
  • The trap distribution throughout the game will be inverted compared to the previous system in that the chance to be trapped on any given floor will now increase as the game progresses, whereas previously trap chances were inversely correlated with XL, so trap chance decreased as the game progressed. Trap effects in the early dungeon will be slightly less common, whereas traps in Zot will be much more common than before.
  • This change was made to combat the tedious gameplay encouraged by the previous system: that is marking of tiles that have been tested by the player or monsters (using systems such as exclusions) and then only stepping on these tiles, in order to reduce the number of times the player was trapped.
  • Worshippers of Ashenzari will be completely protected from this effect upon worship.
• The trap placement system in the hall of Zot and Tomb will be revised so that traps can place on any square, and only net, teleport, Zot, dispersal, and with a lower weight, alarm traps, can place.

History

In 0.23, traps will be overhauled, and the new trap system is described above.

Prior to 0.16, flying players and monsters could avoid triggering traps. Shadow traps were added and trap disarming was removed in this version.

Prior to 0.15, mechanical traps dropped ammunition and all teleport traps were permanent.

Prior to 0.13, mechanical traps were randomly placed throughout every branch.

Prior to 0.12, Traps could be detected by searching (command s).