Arrow Traps are wall-mounted ranged traps that shoot an arrow when something moves through its trigger range.
Arrow traps sense anything moving within 6-7 tiles in front of them, but cannot detect movement above or below their line of sight or through walls.
Once triggered, they immediately fire a single arrow that travels on a straight, horizontal trajectory until it hits a character (dealing 2 HP of damage) or a solid wall.
Once the arrow has been used, the trap is harmless.
It will not fire at monsters that spawn in front of it (such as Bats or Spiders) until they move.
If the arrow can be retrieved, it makes a useful weapon against tough enemies, as it will deal 2 HP of damage to anything it hits, rather than the usual 1 from any other thrown object.
However, the arrow can only be used once as the arrowhead will break off when it hits an enemy. The shaft can be picked up and thrown, but does not hurt enemies so is only really useful for triggering other arrow traps.
Since arrow traps only have a single arrow loaded into them, the usual strategy of disarming them is to trip them by throwing a decoy object into their target zone, such as a rock or pot. Be aware that the rats running around the mines, or the locusts in the temple can trigger the arrow traps as well.
Keep in mind that the arrow will rebound off a wall at a roughly 45 degree angle downwards, so take care when triggering them from below.
If a web happens to spawn in front of one, it will safely catch the arrow when something moves on the other side of the web.
If you have the shield, it will protect you from any arrows that hit you from the front.
It is also possible to use a corpse (such as a Caveman or a Damsel) or even a carried Critter as a 'meat shield' to absorb the shot. This will cause you to drop the body you were holding (or in the case of critters, kill the creature and launch you backwards).
Be aware that this will expend two of a Damsel's three hit points, so do not attempt this with a Damsel who has already taken damage if you intend to sacrifice them or bring them to the exit alive.
Despite the trap's 'line of sight' being 7 tiles long, dropping past an arrow trap far away will cause the arrow to go over your head as you fall faster than the arrow travels.
The faster you are falling, the closer to the arrow trap you can fall and not get hurt. But, beware that the arrow may ricochet off a wall and hit you anyway.
It is also possible to whip an arrow out of the air as it is coming towards you. This is very difficult to pull off as your timing must be exact, but is possible to do if there is no other way. This won't work unless there are at least two spaces* between you and the Arrow Trap.
Another way to successfully disarm the trap (although it takes more steps and only works with a certain set of items) is to break the block behind the trap, using a bomb or the mattock , and then shoot the trap with a shotgun or a freeze ray, which will activate the trap and the arrow will be shot out normally.
(*) You can whip arrows having only one tile between you and the arrow trap, if and only if the arrow trap is facing right. You need no downward momentum to do this. This is likely due to a rounding error which causes the arrow to spawn one pixel further out if the arrow trap is facing left.