In original Dungeons & Dragons, the three brown books only include one rule for traps. “Traps are usually sprung by a roll of a 1 or a 2 when any character passes over or by them.” That’s it. Except for the Find Traps spell, the rules never explain how characters can find traps. In D&D’s original play style, if you wanted to find pit traps, you just told your dungeon master how you pushed down on the floor ahead with your 10’ pole. Or you sent your hireling ahead first. See A Lack of Ability Checks Shaped How People Originally Played Dungeons & Dragons.

In Book III, Underworld and Wilderness Adventures, Gary Gygax lists a dozen tricks and traps such as slanting passages, sinking rooms, and one-way doors. All foiled a retreat from the dungeon. They threatened to make characters lose their way out, or worse, deliver them to a deeper level and more more dangerous foes. None of these traps need rules to play, just player ingenuity.

Undoubtedly, Gary had thought of other traps such as spring blades, poison needles, and warning bells, but his list conspicuously omits any traps that seem to require game-world finesse to overcome.

In the May 1974 issue of a fanzine called the Great Plains Games Players Newsletter, Gary Gygax presented the thief class. In his introduction, Gary tells how the class was suggested by a gamer named Gary Schweitzer (probably Santa Monica gamer Gary Switzer). “He mentioned that his group was developing a new class of character—thieves. Gary gave me a few details of how they were considering this character type, and from from these I have constructed tentative rules for the class.” In 1975, Supplement I: Greyhawk made the class official.

The thief class featured the ability to “remove small trap devices (such as poisoned needles)” At level 1, the thief boasts a 10% chance! So when your new thief says, “Don’t worry, I’ve got this,” the party should dive for cover. Original thieves enjoy no special ability to detect traps. Keep your hirelings in front.

The thief’s limit to disabling “small trap devices” seems to exist as an attempt to confine thieves to working on traps that require a character’s game-world knowledge and dexterity. For example, a chest rigged to release deadly gas requires a thief’s game-world aptitude, and a die roll. Big traps like pits and rolling boulders, which can be beaten through player ingenuity, remain outside of the thief’s skills. Players can tell the DM the steps their characters take to bridge a pit or to chock the rolling-boulder trap.

In the summer of 1975, Gary  brought the Tomb of Horrors to the Origins convention for a D&D tournament. One of the tournament’s players wrote a first-hand account of the event for issue 4 of the Alarums & Excursions fanzine. Even though the party includes two members of the new thief class, the Tomb offers virtually no place for them to disarm traps, and the Tomb [SPOILERS!] is loaded with traps. To determine when players get caught by traps, Gary fills the adventure with an ad-hoc system of saving throws, rolls of 1-2 on a d6, and verbal countdowns. (Player tip: If the DM begins to count down, run!) The Tomb’s legendary status comes from the mix of ingenuity, divination, and attrition required to bypass its memorable deathtraps, rather than the number of disarm checks needed. (DM Tip: if you run the Tomb and allow thieves to detect or disarm much, you’re doing it wrong. The Tomb of Tiresome Checks is a different adventure.) See Tomb of Horrors tests patience, but still ranks as Dungeons & Dragons’ best villain.

In Advanced Dungeons & Dragons, thieves finally gained the ability to locate traps. A low-level rogue’s odds remained dismal, quickly upstaged when the priest gains Find Traps at level 3. This thief ability implied that no one else could find traps—after all, other classes lacked a Find Traps percentage. Third edition set this limitation in the rules by allowing rogues (and only rogues) to find traps “well hidden” behind a 20 or higher Search difficulty.

The rogue or thief’s limit to finding and disarming small traps remained in second edition. “These include poisoned needles, spring blades, deadly gasses, and warning bells,” but do not include “large, mechanical traps.”

In third edition, traps gained a systematic treatment, complete with triggers, effects, and difficulty classes. The Trapfinding ability enabled rogues the chance to locate and disable anything that the DM categorizes as a trap, small or large, magical or mundane. This gave rogues more chances to shine, but heightened the tension between the traps a thief can find and disable and the traps that test player ingenuity. We have all encountered players who insist that a disable trap roll will enable their rogue to easily bypass some elaborate and cunning challenge. So does staying at home, but neither tactic leads to much fun.

When the fourth edition designers rethought D&D, they saw traps as posing two core problems:

• Traps can frustrate players
• Traps can slow play to tedium

Problem: Traps that challenge player ingenuity can lead to player frustration.

This problem arises when when dungeon masters limit the players to a preconceived menu of potential solutions. This approach riddles the Tomb of Horrors, which includes many predicaments that require curiously-specific recipes of spells or actions to escape.

In Traps!, fourth-edition designer Stephen Radney-MacFarland writes, “In the early days, DMs all too often felt compelled to demonstrate their cleverness and punish players for making ‘wrong’ choices—even a choice as simple and random as which passage to explore.” For example, Tomb of Horrors. See Player skill without player frustration.

Problem: Traps can slow play to tedium.

Regarding the problem of slow play, Stephen Radney-MacFarland writes, “The ‘right’ way to play the game was to slowly and laboriously search each 10-foot square of dungeon before you set foot on it, or to use magic that made traps completely pointless. Neither option was much fun.”

Radney-MacFarland never mentions that old-school traps require wandering monsters or some other time pressure to avoid grinding the game to a halt. Of course, if time pressure denied characters the chance to look for the trap that killed them, the hazard seems arbitrary and unfair. See Three unexpected ways wandering monsters improve D&D play.

Fourth edition gives traps a new design

Radney-MacFarland admits designers thought about “disappearing” traps from the game, but decided to try fixing them first.

The fourth-edition design sought to fix the problem of frustrated players by eliminating traps that only challenge player ingenuity. “We wanted to expand the ways in which you could counter a trap. Much like figuring out that sometimes you wanted other skills to allow a character to recognize a trap’s threat, we made an effort to design traps that could be countered with an interesting skill uses.” Skill checks became the core mechanic for resolving traps. The game invited dungeon masters to allow as many different skills as plausible so everyone could share the fun of making skill checks.

Many players prefer traps that require ingenuity to overcome, because such challenges make the players’ decisions matter in the game world. But not all players favor this play style. The fourth edition design aimed to please players who insisted that a disable trap roll enabled their rogue to easily bypass some elaborate and cunning challenge. Still, the designers recognized that turning traps into a cause for skill checks failed to offer enough fun, so they redesign went farther.

“Most traps work best when they ‘replace’ a monster in a combat encounter, or serve as a hazard equally threatening to both sides.” In fourth edition, traps become a sort of stationary monster that the characters can disable or attack. Like monsters, traps make attacks, grant experience, and have solo and elite varieties. In this new concept, traps add spice to combat encounters, allow rogues to strut their skills, and target monsters as well as players—a new tactical element.

Radney-MacFarland writes, “Don’t fret, rogue fans. That class and other characters trained in Thievery are still the party’s best hope to shut down traps quickly and well.” But fourth-edition rogues soon learned to approach traps like everyone else, by attacking. Fourth-edition rogues inflict so much damage that a series of thievery checks always took longer than just attacking a battlefield trap.

Justifying battlefield traps

In the game world, the battlefield trap always seemed hard to justify. I pity dungeon builders stupid enough to bother enchanting, say, an automatic-crossbow trap rather than an iron defender or other construct. Unlike constructs, traps (a) cannot move, (b) can be disabled, and (c) will attack your guards as well as intruders. The dungeon builder’s henchmen, hired to fight alongside their master’s indiscriminate death machines, should look for a job at a better class of dungeon.

The fourth-edition approach to traps never proved as satisfying as hoped. As the edition evolved, we saw a gradual return to classic traps, even with all their problems.

Fifth-edition traps

Although complex traps revisit the good ideas from fourth edition’s battlefield traps, most fifth-edition traps recall the ones from before fourth edition. The rules offer advice for avoiding the problems with traps. “Traps are most effective when their presence comes as a surprise, not when they appear so often that the characters spend all their effort watching out for the next one.”

Just like thieves in D&D’s original game, fifth-edition rogues lack any special ability to find traps. Now, to find a trap, any character can attempt a Wisdom (Perception) check. The rules specifically allow players to find traps by looking in the right places. “You should allow a character to discover a trap without making an ability check if an action would clearly reveal the trap’s presence. For example, if a character lifts a rug that conceals a pressure plate, the character has found the trigger and no check is required.”

Depending on the trap, the best way to disarm may be a Dexterity or Strength check, but player ingenuity often works. “As with many situations, you shouldn’t allow die rolling to override clever play and good planning.” If disarming a device requires a check, the rogue’s proficiency with thieves tools can help.

Ironically, rogues rarely have high Wisdom, so they rate as bad at finding traps. Lucky for today’s rogues, the class pivoted from unlock-and-disarm specialists to hidden snipers. See The Thief’s Strange Trip From Non-Combatant to Battlefield Domination.