Alarm trap

Version 0.31: This article may not be up to date for the latest stable release of Crawl.

A trap that creates a loud noise to attract nearby monsters. In addition to the noise it creates, it will apply an enchantment making monsters all over the level aware of your location. Hostile monsters may trigger this trap themselves to invoke its effects against you, but your allies will avoid stepping on it.

An alarm trap is a trap which produces an extremely loud noise at its location, and inflicts the Mark status to the player, attracting monsters to your location. Even if a monster steps on a trap, you are still marked. After triggering once, they disappear. Like all traps, flight cannot be used to avoid them.

Alarm traps can be silenced, preventing the noise, but this does not prevent the Mark status:

The alarm trap vibrates slightly, failing to make a sound.

Strategy

• Being silenced will reduce the number of monsters lured in. You'll still get the Mark status, but only awake monsters are attracted by Mark, and most monsters are asleep when you enter a new floor.
• You can step onto the trap, then quickly rush upstairs. This will wake everything up, but they won't be able to swarm you nearly as easily.
  • Note that if all 3 upstairs are close to each other, doing this is dangerous. No matter which stair you descend to, you'll probably be next to a huge clump of monsters.
• Quaffing a potion of cancellation ends Mark immediately, removing monsters' ability to track you. Thus, you can teleport without a swarm of monster chasing after you. Even if you don't teleport, the monsters are likely to forget your location. Note that these potions are rare, however.
• If all else fails and you need to make a last stand, you'll usually have a few turns free before the horde arrives; consider using that time to create a killhole, and don't be afraid to teleport if it's clearly going badly for you; all those enemies clustered around your old location will need a lot of time to catch up with you, during which you might be able to escape the floor or lose the status effect naturally.
• You can use the trap on an almost cleared floor to lure all remaining monsters to you or to check that there are no monsters left.

History

• Prior to 0.23, alarm traps didn't Mark the player when monsters stepped on them. Also, monsters could trigger these traps while out of the player's line of sight.
• Prior to 0.12, alarm traps could activate multiple times before breaking, but they were not quite as loud and did not afflict you with the Sentinel's Mark.