Nothing delights a trap builder, and thus the GM, more that designing a trap that adventurers want to charge into. The easiest way to avoid a trap is to simply walk away from it, so you have to make it just too irresistible to be avoided. This can be done by making some aspect of the setup very interesting, including some object or information needed elsewhere in the dungeon or simply adding some treasure. (The idea of using the right bait was covered in Trapmaster: Enough Rope to Hang Themselves.)
This chapter takes it a step further by trapping objects that the party wants to take with them, only to discover the horror of their prize later. Jaded adventurers see treasure and always check for traps on the altar, floor, ceiling, and chest… but when was the last time they searched the treasure itself? Presented here are three devious trapped objects that the characters can take home to bedevil them at a later date—just when they think they’re safe!
Simple trap (level 1–4, deadly threat)
The knockout cane packages a nonlethal punch into an elegant package. The cane has a jade-inlaid pommel shaped like the head of a green dragon. A successful DC 13 Wisdom (Perception) check is needed to discover that it is in fact a cleverly hidden rapier sword cane. In addition to be useful as a weapon, its quality and style make it worth 50 gp.
Unfortunately, when the sword is drawn from the activated cane scabbard, knockout gas surrounds the wielder, potentially leaving them vulnerable to their enemies.
Trigger. The first time the sword is drawn without pressing a stud disguised as the fourth of the teeth on the right side, the trigger inside the cane becomes active. This allows a looter or prospective buyer to safely inspect the sword… and set the trap. The second time the sword is drawn, a cloud of poison gas is triggered
Effect. When the cane is triggered, knockout gas fills a 5-foot cube centered on the wielder who must succeed on a DC 20 Constitution saving throw or be knocked unconscious for 1 hour. A successful saving throw resists the poison. A creature that fails the saving throw may attempt another to wake up if it takes damage or if another creature takes an action to shake it awake.
Countermeasures. A successful DC 20 Wisdom (Perception) check notes that one of the teeth is a button. Pressing it while drawing the sword resets the trigger to off. A successful DC 20 Intelligence (Investigation) check notes that the cane’s balance seems off, as if there is a liquid filled compartment at the bottom. Breaking open the cane sheath sets off the trap.
Quicksilver Plate Mail
Simple trap (level 5–10, dangerous threat)
Originally created by the gelugon smith X’xiritz, these suits of armor are sold only to those who do not carefully read their infernal contracts or those who wish to leave something dangerous for looters to take home. Because of its nature, this suit of +1 plate is found only in deeply cold places that are well below freezing.
The armor is made of frozen mercury, magically hardened, so it can be worked without becoming brittle. The armor is then enameled with a blue-and-white snowflake motif. Unfortunately, when worn, the armor heats up quickly and melts, covering the wearer in poisonous mercury.
Trigger. Once the armor is brought above −38°F (−39°C), the armor melts within 1 minute.
Effect. The armor melts faster than it can be removed, forcing the wearer to succeed on a DC 15 Constitution saving throw or become poisoned. While poisoned, the creature’s hit point maximum is decreased by 11 (2d10). Each time the character finishes a long rest, they must attempt a DC 15 Constitution saving throw. A successive save means the character is no longer poisoned. A failed save decreases the characters hit point maximum by an additional 11 (2d10). The target dies if their hit point maximum is lowered to 0. The hit point maximum reduction lasts until the character is no longer poisoned.
Secondary Effect. The armor is destroyed and no longer useable.
Countermeasures. A successful DC 20 Intelligence (Nature) check recognizes that the armor is made out of dangerous mercury. Dwarves and characters proficient in blacksmithing tools gain advantage on this check. Creatures without body heat, such as undead or constructs, can safely wear the armor as long it is kept properly cold.
Simple trap (level 11–16, deadly threat)
This leather gauntlet is decorated with an image of a martial artist wielding a flaming gauntlet. The fingers are studded with pointed crystals, and within each dances a tiny flame. The gauntlet radiates evocation magic if checked for with a detect magic spell, as would be expected for a weapon that deals fire damage. The gauntlet certainly seems to imply that punching a foe will cause it to suffer fire damage… unfortunately, so will the wearer.
Trigger. Any violent impact on one or more of the crystals causes them to shatter, causing a massive explosion. Any crystals not broken by the impact shatter in the explosion.
Effect. A 20-foot-radius sphere of fire explodes outward from the gauntlet, destroying the gauntlet and dealing 99 (18d10) fire damage to all creatures within range. A successful DC 20 Dexterity saving throw halves the damage. A creature wearing the gauntlet makes this saving throw with disadvantage.
Secondary Effect. The flames ignite flammable objects in its area that aren’t being worn or carried.
Countermeasures. Don’t hit things with the gauntlet. Only an identify spell or similar magic reveals the true danger.