Container trap

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Chests and large boxes each have a 10% chance of being protected by a container trap. If you apply, loot or kick open a trapped container, or use an unlocking tool to lock or unlock it, the trap will be set off. The #untrap command checks a container for traps, and will prompt you to disarm it if one is found. Unsuccessfully disarming a trap will also set it off.

The type of trap on a trapped container is not determined until it is set off.

Wishing for a “poisoned” large box or chest will create one that is guaranteed to be trapped.


Use the #untrap command on your current square (.) to search a container in that square for traps. If a trap exists on a container, the chance of actually finding it is 10/(31 - Xlvl).[1] This is a 1/3 chance at experience level 1, increasing to 100% at level 21. If you are confused, the chance of success is always 1/3. Searching for a container trap will never set it off, even if you fail to find it.

When a trap is found, you are given the option of disarming it.

Your proficiency at disarming traps is (Dex+Xlvl), which is doubled if you are a Rogue. The difficulty of a particular trap is [75+(Dlvl/2)], based on the current dungeon level when you try to disarm the trap.

If a roll of d(difficulty) is less than or equal to your proficiency, and you are neither confused nor fumbling, the trap is disarmed (“You disarm it!”).[2] Otherwise, the trap is set off as normal. In either case the container is no longer trapped.

You can also #invoke the Master Key of Thievery to remove a container trap, with no chance of setting it off.

Trap effects

When you set off a trap, there is a chance that it will be harmless. This occurs if d(13+Luck) > 8. If so, you will randomly receive one of the following meaningless messages:[3]

  • But luckily the explosive charge is a dud! (2/13 chance)
  • But luckily the electric charge is grounded! (2/13)
  • But luckily the flame fizzles out! (2/13)
  • But luckily the poisoned needle misses! (3/13)
  • But luckily the gas cloud blows away! (4/13)

Otherwise, a number will be chosen between 0 and 25. There is a 1/20 chance that this will be randomly chosen from the full range; otherwise the number will be between 0 and (13-Luck). The effect of each result is as follows:[4]

Number Message Effect
21–25 The <container> explodes!
  • The container, its contents, and all objects in the same square are destroyed.
  • If any of these items belong to a shopkeeper, you will be liable for the cost. If you are somehow not in a shop, the shopkeeper will also become angry.
  • You lose 6d6 hit points and abuse Strength.
  • You wake nearby monsters.
17–20 A cloud of noxious gas billows from the <container>.
  • You are poisoned, if you are not poison-resistant.
  • There is a 1/15 chance that the poison is deadly.
  • There is a 5/15 chance that the poison drains 3–5 points of Strength.
  • Otherwise, the poison deals 6–15 damage.
  • You abuse Constitution, even if poison-resistant.
13–16 You feel a needle prick your <hand/finger>.
  • You are poisoned, if you are not poison-resistant.
  • There is a 1/10 chance that the poison is deadly.
  • There is a 5/10 chance that the poison drains 3–5 points of Constitution.
  • Otherwise, the poison deals 6–15 damage.
  • You abuse Constitution, even if poison-resistant.
9–12 A tower of flame bursts from the <container>!
6–8 You are jolted by a surge of electricity!
3–5 Suddenly you are frozen in place!
  • You are paralyzed for 5d6 turns, if you do not have free action.
  • You abuse Dexterity, but only if you do not have free action.
0–2 A cloud of <color> gas billows from the <container>.


Container traps can be very dangerous, especially if you lack poison resistance, fire resistance and free action. It is a good idea to search each chest and box you find for traps. Since characters below level 21 are not guaranteed to find a trap even if one exists, you should check at least 2–3 times.

Luck has a strong effect on traps. If you have maximum Luck (13), 69% of traps will be harmless, compared to only 38% at 0 Luck. If your Luck is at least 8, only 0.6% of traps will be electricity traps.

Remember that once you find a trap, you can safely choose to leave it undisturbed. This might be a good idea in the early game, when your Luck is low and the consequences of setting off a trap are especially severe.

You can increase your chances of disarming a container trap by dragging the container to a shallower dungeon level. However, since trappable containers are heavy and the effect is small, this is probably not worth the effort.

Once you have reflection, an electricity trap is one of the few effects that can still destroy your rings and wands. If you are in an area with many chests, such as the Priest quest, Vlad's Tower or the Valley of the Dead, it might be a good idea to put them away temporarily.


This page may need to be updated for NetHack 3.6.0.

It may contain text specific to NetHack 3.4.3. Information on this page may be out of date.

Editors: After reviewing this page and making necessary edits, please change the {{nethack-343}} tag to {{nethack-360}} or {{noversion}} as appropriate.