Trap design

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v50.13 · v0.47.05

This article is about the current version of DF.
Note that some content may still need to be updated.

This page is one of several inter-related articles on the broader topic of defending your fortress and your dwarves. Trap design focuses on the theory and design of complex traps, mechanical systems and other automation for defending your fortress, and also on unusual uses of simple mechanic's traps. For a general overview of the threats that will challenge your fortress and things to consider when preparing a standard defense, see the defense guide. For tips on laying out your architecture to protect your military, see security design. For specific advice on how to get your soldiers prepared for any threat, see military.

For suggestions on disposing of nobles and other unwanted residents, see unfortunate accident.

For a basic overview of how the different machine parts work and work together, see machine component.

For information on catching vermin-sized creatures in animal traps, see trapper.

Introduction

Simple one-tile traps* are just that – they exist only on their own tile, trigger themselves when a target walks onto that one tile, and affect only that one tile. Complex traps and automation rely on linking doors, hatches, floodgates, and bridges to levers or pressure plates, along with machinery to provide the power to run some of the more diabolical designs. When the trigger is activated, it sends a signal to the linked device. That signal is not always as simple as do it now, but it's specifically either to open or to close. By manipulating what does what and when, and what follows from that, impressive results can be achieved.

(* specifically, the stone-fall trap, weapon trap, and cage trap.)

To fully understand how these component objects work individually (before combining them into diabolical and complex combinations), see those main articles.

Basic traps

These are the simple traps that are placed by a mechanic. They require one mechanism but do not require levers or pressure plates. They can be a quick, easy and brutally effective "first defense" for a fledgling fortress, but they can also be combined into key parts of more complex set ups. For tips on using these basic traps effectively, see the Trap Strategies section.

Stone fall trap

This is the easiest trap to build, so you can easily build them in large numbers. Building lots of them is an easy way to earn experience for your mechanic, and add to the depth of your fort's defenses at the same time. Surrounding intersections and stairways is a good way of handling threats that make it inside the fortress, including berserk dwarves.

Weapon trap

The gold standard of lethal traps. This is the only simple trap that works repeatedly without reloading. They do get jammed, however. View the trap with the items in room t mode, and if there's a corpse inside the trap, it's jammed. None of the weapons on a jammed trap will function. It may be wiser to have several weapon traps with fewer weapons, rather than a smaller number of ten-weapon traps.

Using crossbows or other projectile weapons in weapon traps avoids the problem of jamming, but they must be kept loaded with ammo. Mechanics will load them with any ammo that is not forbidden. They will load each until each type of weapon has ten rounds of ammo. Hammers seem to jam less than swords or axes, and spears seem to jam the most. Your dwarves will attempt to unjam traps unless otherwise forbidden.

Cage trap

A very powerful type of trap. Maybe even too powerful – currently, even a wooden or glass cage can hold any creature indefinitely, even trolls and megabeasts. A cage trap never fails, although creatures with the trapavoid tag cannot be captured unless knocked unconscious or webbed first. Use cage traps as your outermost traps to catch the occasional wandering animal, angry wounded elephant or unicorn, or even zombies. Caged animals and enemies will be safely brought to any animal stockpiles you have, but may escape later if you are not careful. For more information, see captured creatures.

Linked traps

These traps require a trigger such as a pressure plate or lever. They will require at least three mechanisms, one for the trigger and two to create the link. The trigger can be located any distance from the trap, typically close for a pressure plate or far away for a lever.

For a system that repeatedly activates automatically and regularly regardless of enemies, see Repeater.

Menacing spikes

Menacing spikes or upright spears appear on the basic mechanic's Trap menu, but must be activated remotely to pop out of the ground and impale anyone standing on that tile. Vast forests of these can make any area a killing field.

While upright spike defense systems never jam, they also do not discriminate. When activated, they will inflict piercing damage on whatever is standing on the tile, whether it be friend or foe (so it's good for nobles). You can use traffic designations to help somewhat. Designate the spike trap tiles as restricted then make a longer path going around the spikes that's designated as high traffic. Pets and merchants/diplomats will probably still get skewered, though.

Trap strategies

These are some basic tricks that can be used with most any trap design, basic or complex.

Bait animals

Enemies will hunt down and kill friendly tame animals wandering outside if they have nothing better to do. Put an expendable animal on a restraint or in a 1x1 pen in some random spot outside, build a few columns around it to reduce the chance of them shooting it, and trap that area to hell and back.

Note that this is a horrible method of getting rid of cats, as they will often adopt a dwarf who will then attempt to free the cat. This may lead to the unfortunate situation of Urist McCatlover getting skewered by an ambush party while on his way to free Mr. Baitykins.

Bait furniture

Building destroyers can be baited by furniture, which they will path to and destroy, if they can. Furniture bait allows you to selectively target building destroyers, to draw them away from other aggressors or to a different trap. This can be useful when, for instance, you'd like to draw a building destroyer like a giant cave spider into a cage trap, but don't want to bother caging all of the other wildlife around it. It can also be useful for trapping monsters with special attacks that you'd rather not see go off, as the building destroyer won't use any special attacks on furniture as it would an animal. For instance, you could use bait furniture to trap a forgotten beast with deadly dust without causing it to spew more contagion.

Bait furniture can be especially effective when used with artifact quality furniture. Artifact furniture cannot be destroyed, but building destroyers will still attempt to path to it, at which point they will ineffectually attempt to destroy the furniture. This makes traps baited with artifact furniture easily reusable.

Trapping efficiently

Crosshair trapping

As the converse of building many traps everywhere, consider instead herding your enemies into a few traps. A cross-hair pattern of walls or impassable channels with an array of traps in the middle gap will increase the usage of each individual trap. This is particularly useful when capturing wildlife. You may also want a few traps near the edges, to catch the creatures that attempt to go around it.

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