Spike trap

A spike trap is a single-use trap that deals heavy, but material dependent damage to the pawn that triggered it.

Acquisition

Spike traps require 45 Stuff (Metallic/Woody/Stony, 450 for SMVs), 3,200 ticks (53.33 secs) of work, and a Construction skill of 3. Spike traps cannot be placed or constructed directly next to each other nor next to any other kind of trap.

Summary

Spike traps are single use traps that may be triggered when a pawn of any kind walks over it.

The base trigger chance is 100% for enemies, including animals affected by the manhunter mental state. Note that despite the name, animals currently hunting a human pawn for food are not "manhunters" and are not considered enemies.
Non-manhunting wild animals have a 25% chance to trigger the trap.
Colonists and tame animals have 0.4% (one in 250) to trigger the trap.
Friendly visitors will never trigger a trap.

However, colonists and non-manhunting animals are aware of the location of traps, and will avoid pathing over them if reasonably possible. In all instances, the nimble trait multiplies the trigger chance for that pawn by 10%, that is, a 10% chance for enemies and 0.04% chance for friendly pawns.

Once a spike trap is triggered, it is destroyed. The "auto rearm" option, enabled by default, produces a blueprint to replace the trap.

Damage

When triggered, the spike trap makes five attacks against the pawn that triggered it. Each attack does Stab damage. This strikes mainly on the head and torso and usually causes bleeding. The amount of damage dealt by each attack is determined by the following equation:

Damage Per Attack = Trap Melee Damage * Material Sharp Damage Multiplier * rand(0.8, 1.2)/5

Where:

Damage per Attack is the damage each attack does to the target. A spike trap performs 5 of these attacks when triggered.
Trap Melee Damage is 100 for spike traps
Material Sharp Damage Multiplier is a material dependent factor.
rand(0.8,1.2) is a random factor between 0.8 and 1.2. This random factor is rolled once only and then applied to all attacks, it is not rolled for each attack.

The armor penetration of the attack is determined by the following equation:

AP = Damage Per Attack * 0.015

AP is the armor penetration of each attack.

Note that both the damage and AP of the attack in the info screen are misleading. The damage listed is the average sum of the damage inflicted, the AP is incorrectly calculated as if this damage is all dealt at once.

Analysis

For tips on how to use spike traps in general or in killboxes, see Defense structures#Spike traps and Defense structures#Entryways.

Spike traps are invaluable in the earlygame, as one of the few defense strutures available. A hallway of spike traps can virtually end any frontal raid, short of tough or nimble pawns, without your colonists ever seeing combat. A single trap can be fatal to humans or large animals. Multiple traps can fall most creatures, short of thrumbos and heavy mechanoids. But as raids get bigger, it starts to get impractical to replace the traps.

Place traps where you expect raiders to go. Raiders will take the shortest, unobstructed route to a target. Unless they are sappers or breachers, raiders will try and break walls last. Common locations are in the corners of your base, where enemies will likely make turns, as well as narrow areas that receive frequent traffic. If it doesn't seem obvious to you at first, one way to find out is by studying raids that do come.

Material choice

Wood spike traps can be quickly created and placed in large quantities. Stone spike traps are cheap to make, and can kill a humanoid raider in one trap. But given the significantly increased crafting time of both the traps themselves and the stone blocks required to build them, it is often more efficient to simply make several wooden traps. Stone traps are helpful if you're limited by space or type of resource available, and can be a good activity when one has the Work Frenzy Mental inspiration. Metal traps are even stronger and don't take as much time to make, but are expensive in terms of resources.

Example of a trap tunnel. Raiders will fall into the traps. Colonists can open doors, and prefer to be slowed by the fences rather than walk through traps. If this is the only open entrance to a base, raiders will be lured here.

Stats table

Spike trap	Beauty	Work to Build	HP	Flammability	Total Damage	Attack Damage	Armor Penetration	Market Value
Material	Beauty	Work to Build	HP	Flammability	Total Damage	Attack Damage	Armor Penetration	Market Value
Bioferrite	-18	008,000 ticks (2.22 mins)	80	75%	130	26	39%	63
Gold	2	002,880 ticks (48 secs)	24	40%	75	15	22.5%	4,510
Granite blocks	-18	019,340 ticks (5.37 mins)	68	0%	65	13	19.5%	110
Limestone blocks	-18	019,340 ticks (5.37 mins)	62	0%	60	12	18%	110
Marble blocks	-17	017,740 ticks (4.93 mins)	48	0%	60	12	18%	104
Plasteel	-18	007,040 ticks (1.96 mins)	112	0%	110	22	33%	430
Sandstone blocks	-18	016,140 ticks (4.48 mins)	56	0%	50	10	15%	99
Silver	-12	003,200 ticks (53.33 secs)	28	40%	85	17	25.5%	460
Slate blocks	-18	019,340 ticks (5.37 mins)	52	0%	60	12	18%	110
Steel	-18	003,200 ticks (53.33 secs)	40	40%	100	20	30%	97
Jade	-8	016,000 ticks (4.44 mins)	20	0%	100	20	30%	285
Uranium	-18	006,080 ticks (1.69 mins)	100	0%	110	22	33%	290
Wood	-18	002,240 ticks (37.33 secs)	26	100%	40	8	12%	62

Version history

0.11.877 - Added as Deadfall Trap.
0.12.910 - Rebalanced, cannot be rearmed.
0.19.2009 - Renamed from Deadfall trap to Spike trap. Damage is increased, material cost and time to build are reduced, and it now has armor penetration (depending on what it’s made of) and a 100% chance to spring on targets and but now require rebuilding each time, rather than being re-armed at no material cost.