Trap · Game Mechanic Compendium

Definition

A trap is a device, glyph or mine that the user places and leaves; it acts on its own when an opponent enters, touches or reads it, usually once. Stun and slow are common payloads, and the trap is their delivery. A totem acts: it chooses targets and fires again and again, while a trap waits for contact. A barrier’s placed wall stops passage for everyone; a trap lets the victim in and then acts. Reveal detects traps, and a trap that exposes its victim remains a trap. Hazards set by the designer or referee are level design, and tower defence is the wave-and-path structure in which traps are one tool.

Behaviour

The trap sits on the ground or on a door, chest or book while the user acts elsewhere. Triggers are passing, touching, opening or reading, or entering a radius or hex, and many exempt someone: Symbol the caster’s alignment, Glyph of Warding whoever speaks its name. Concealment protects it: Fire Trap halves the chance of detection, and Techies’ mines evade True Sight. Counterplay is detection, dispelling and avoidance; Gloomhaven monsters route around trap hexes, so forcing them in is a tactic. Damage traps are a large minority, but every form denies a spot or path.

Variations

Warding glyph (Greyhawk, Advanced Dungeons & Dragons): an inscription with a payload chosen at casting, from sleep to fire or death.
Trapped object (Explosive Runes, Fire Trap): fires when a book, chest or door is opened or read.
Holding trap (Heiankyo Alien, World of Warcraft Freezing Trap, Dead by Daylight, Monster Hunter Wilds): binds or freezes the victim until time, damage, struggle or an ally frees it, sometimes to set up a finishing action.
Proximity mine (Dota 2, League of Legends): an invisible damage charge laid in numbers; Noxious Trap adds a slow and a reveal.
Field trap (World of Warcraft Frost Trap): affects every enemy within a radius once sprung.
Alarm (Greyhawk Magic Mouth): a spoken warning, bordering reveal.

Gating

Tabletop traps of 1975 to 1978 are slot spells, but setup is the larger price: casting takes rounds, a glyph is traced square foot by square foot, and a large one consumes 2,000 gp of diamond. A trap lasts until discharged, so one set in advance escapes the daily spell budget. Heiankyo Alien’s dig is free but slow. World of Warcraft adds mana, a cooldown, one active trap and no placement in combat. MOBAs use refilling charges and cap the field by lifetime and spacing; Dead by Daylight’s Trapper carries one trap. Gloomhaven prints traps on ability cards, and Monster Hunter Wilds crafts them. The user pays to place; the victim’s movement triggers.

History and provenance

The earliest documented use cited is Greyhawk (1975), whose Symbol takes effect when “passed over, touched, or read” and whose Explosive Runes guard a parchment; the text cited is a 1979 printing, so the 1975 wording is unconfirmed. The 1974 Mirror of Life Trapping, a found item that traps whoever looks into it, is a borderline antecedent. The 1974 spell lists hold only the detection spell Find Traps. The 1978 Players Handbook adds Glyph of Warding, Fire Trap, Snare and Trip. Heiankyo Alien (1979), from the University of Tokyo’s Theoretical Science Group, is the earliest video case cited; its only weapon is a pit.

Notable examples

Notable examples, in chronological order. Notes describe how the ability behaves in each game; gating is what limits its use there; the latest reference is a widely played game from 2020 or later.
Game	Year	Medium	Gating	How the ability behaves
Dungeons & Dragons Supplement I: Greyhawk Gary Gygax and Robert Kuntz (TSR)	1975	Tabletop RPG	Spell slots	Symbol, an 8th-level magic-user spell, is an inscribed rune that takes effect when "passed over, touched, or read" by a creature of another alignment or hostile intent, with fear, discord, sleep, stunning, insanity or death. Only a magic-user a level above the caster can negate it. Explosive Runes (3rd level) on a parchment deal 4-24 to an unauthorized reader, with no save.
Advanced Dungeons & Dragons, Players Handbook Gary Gygax (TSR)	1978	Tabletop RPG	Spell slots, Consumable	Glyph of Warding (cleric 3rd) guards a bridge, entry or chest and turns invisible; touching it without speaking its name releases shock or fire (2 per caster level), paralysis, blindness or level drain, and over 50 square feet it needs 2,000 gp of diamond. Fire Trap (magic-user 4th, druid 2nd) on a closable item blasts 5 feet for 1-4 plus 1 per level.
Heiankyo Alien Theoretical Science Group, University of Tokyo	1979	Video	At will	The player has no attack and digs a pitfall in five stages; aliens fall only into a finished hole, and the player must then fill it in, in five more stages, to remove the alien. A trapped alien climbs out after a while or is freed by another alien, and small holes are walked over.
World of Warcraft Blizzard Entertainment	2004	Video	Mana, Cooldown	In the strategy guide's values, hunter traps are placed at the hunter's feet. Freezing Trap (50 mana, 15-second cooldown at rank 1) freezes the first enemy that approaches, "preventing all action" for up to 10 seconds until damage breaks it; Frost Trap slows enemies within 10 yards to 40%. Each trap lasts a minute, one may be active, and none can be set in combat.
League of Legends Riot Games	2009	Video	Mana, Charges	In current-patch values, Teemo's Noxious Trap is a stealthed mushroom that detonates when stepped on, slowing, damaging over time and revealing the victim; it lasts minutes and holds 3 charges at 75 to 35 mana. Caitlyn's Yordle Snap Trap, with 2 charges, reveals and immobilizes an enemy champion for 1.5 seconds.
Dota 2 Valve	2013	Video	Mana, Charges	In current-patch values, Techies' Proximity Mines are invisible even to True Sight and detonate when an enemy stands within 500 units for a second, dealing 400 to 700 damage, halved at the edge, and lowering magic resistance. Each costs 110 to 170 mana from 3 charges that restore every 15 seconds, and lasts until it explodes.
Path of Exile Grinding Gear Games	2013	Video	Mana, Cooldown	Trap skills throw a device that acts when triggered; Explosive Trap creates a large explosion when triggered, and since 3.3.0 up to 15 traps may be active (from 3). That patch removed the cooldowns of Fire, Lightning and Ice Trap, while Bear Trap kept one and debuffs its target.
Dead by Daylight Behaviour Interactive	2016	Video	Charges	The Trapper sets bear traps, which immobilise and injure a survivor who steps in until the survivor struggles free or another frees them. In current rules he carries up to two, picks up more from eight that spawn disarmed around the map, and can be caught by his own armed traps.
Gloomhaven Isaac Childres (Cephalofair Games)	2017	Board & card	Action cost, Per rest, Consumable	Character ability cards can "create traps on the board", each with the effect its card states. A trap springs when a figure enters its hex by normal or forced movement, flying and jumping figures excepted, and is then removed. Monsters treat trap hexes as obstacles unless no other path exists, so pushing or pulling them in is a tactic.
Monster Hunter Wilds Latest Capcom	2025	Video	Consumable	A Shock Trap or Pitfall Trap is set on the ground where the monster will walk into or touch it, and holds the monster so that Tranq Bombs can capture it; Pitfall Traps suit larger monsters that resist Shock Traps. Each is crafted from a Trap Tool and a Thunderbug Capacitor or a Net, and the pouch holds two Trap Tools and one trap of each type.

Provenance

Earliest documented use: Dungeons & Dragons Supplement I: Greyhawk (1975), tabletop rpg. Confidence: medium. Greyhawk's Symbol, a rune that takes effect when "passed over, touched, or read" by a creature of hostile alignment or intent, and its Explosive Runes, which explode on an unauthorized reader, are the earliest player-placed traps cited. The text cited is the 12th printing of November 1979, and whether the 1975 first printing carried the same wording is unconfirmed. Dungeons & Dragons (1974) offers a borderline antecedent: the Mirror of Life Trapping, which "can be set up to operate untended" and traps whoever looks into it, is a found item triggered by a look rather than an ability triggered by contact. The 1974 spell lists hold no trap spell, only the detection spell Find Traps, and the referee's pits and traps in the same rules are environment rather than an ability. Glyph of Warding, Fire Trap, Snare and Trip are first documented in the 1978 Players Handbook. Heiankyo Alien (1979) is the earliest video case cited; whether any earlier video game had a player-set trap remains unsurveyed, as do 1974-1975 fanzines.

Sources

Gary Gygax and Robert Kuntz. (1975). Dungeons & Dragons Supplement I: Greyhawk. TSR. Rulebook Explanation of Magic-User Spells: 2nd level (Magic Mouth) and 3rd level (Explosive Runes), p. 22; 8th level (Symbol), p. 26; Cleric 7th level (Symbol), p. 32. Accessed 2026-10-24. Symbol's trigger, its six runes and its negation rule; Explosive Runes' 4-24 damage with no save; Magic Mouth as a placed alarm. The scan is the 12th printing, November 1979.
Gary Gygax. (1978). Advanced Dungeons & Dragons, Players Handbook. TSR. Rulebook Cleric Spells (3rd Level), Glyph of Warding, pp. 47-48; Druid Spells (2nd Level), Fire Trap and Trip, c. pp. 56-57; Druid Spells (3rd Level), Snare, c. pp. 60-61; Magic-User Spells (3rd Level), Explosive Runes, p. 73; (4th Level), Fire Trap, p. 77. Accessed 2026-10-24. The 1978 trap spells, the glyph's payloads and diamond cost, Fire Trap's trigger, blast and reduced chance of detection, and the holds of Snare and Trip.
Gary Gygax and Dave Arneson. (1974). Dungeons & Dragons, Volume 1: Men & Magic. Tactical Studies Rules. Rulebook Spells Table; Explanation of Spells (Find Traps, Hold Portal, Wizard Lock). Accessed 2026-10-24. The 1974 spell lists, which contain a trap-detection spell and locks but no trap spell.
Gary Gygax and Dave Arneson. (1974). Dungeons & Dragons, Volume 2, Monsters & Treasure. Tactical Studies Rules. Rulebook Explanations of Magic Items: Miscellaneous Magic, Mirror of Life Trapping, p. 38. Accessed 2026-10-24. The mirror that traps the life-force of whoever looks into it and can operate untended, the borderline 1974 antecedent.
Gary Gygax and Dave Arneson. (1974). Dungeons & Dragons, Volume 3: The Underworld & Wilderness Adventures. Tactical Studies Rules. Rulebook The Underworld, procedures (traps and pits sprung on a 1 or 2), c. p. 9. Accessed 2026-10-24. Referee-placed traps sprung by a die roll as characters pass, the environment form outside the ability.
Theoretical Science Group. Heiankyo Alien, Overview. Website Overview; rules. Accessed 2026-10-24. Development by the Theoretical Science Group at the University of Tokyo in summer 1979, and the dig, fall-in and fill-in rules.
Michael Lummis and Danielle Vanderlip. (2005). World of Warcraft: Official Strategy Guide. BradyGames. Book Hunter chapter: Outdoorsmanship (Freezing Trap, Immolation Trap, Frost Trap, Explosive Trap). Accessed 2026-10-24. Trap mana costs, the 15-second cooldown, the one-minute lifetime, one trap active at a time, no placement in combat, and Freezing Trap's 10 to 20 seconds.
Riot Games. Data Dragon champion data, Teemo (version 16.21.1). Website Noxious Trap. Accessed 2026-10-24. The stealthed mushroom trap, its slow, damage over time and reveal, its 3 charges and mana cost, in current-patch values.
Riot Games. Data Dragon champion data, Caitlyn (version 16.21.1). Website Yordle Snap Trap. The trap that reveals and immobilizes an enemy champion for 1.5 seconds, with 2 charges.
Valve. Dota 2 hero data, Techies. Website Proximity Mines. Accessed 2026-10-24. The invisible mine, its 500-unit trigger radius and one-second delay, damage, magic-resistance reduction, mana costs, 3 charges with a 15-second restore, and the 350-unit spacing rule, in current-patch values.
Isaac Childres (Cephalofair Games). (2017). Gloomhaven rulebook. Rulebook Overlay tiles: Traps, p. 14; Monster Interaction with Traps and Hazardous Terrain, p. 31. Accessed 2026-10-24. Scenario traps against traps created by character abilities, springing on entry by normal or forced movement, and monster avoidance of trap hexes.
Aimee Hart. (2022). Dead by Daylight The Trapper build guide. Gfinity Esports. Article Accessed 2026-10-24. The Trapper carries one bear trap and collects others placed around the map; a caught Survivor is immobilised until freed by escape attempts or a teammate.
Sam Chandler. (2025). How to trap monsters - Monster Hunter Wilds. Shacknews. Article Accessed 2026-10-24. Placing Shock and Pitfall Traps where the monster walks into or touches them, the hold for capture with Tranq Bombs, and Pitfall Traps for monsters that resist Shock Traps.
Sam Chandler. (2025). How to craft traps - Monster Hunter Wilds. Shacknews. Article Accessed 2026-10-24. The trap recipes and the pouch limits.
Grinding Gear Games. (2018). Path of Exile: Incursion (Content Update 3.3.0) Patch Notes. Website Accessed 2026-10-24. Explosive Trap and Seismic Trap, the active-trap limit raised from 3 to 15, and cooldowns removed from Fire, Lightning and Ice Trap but kept on Bear Trap.
Mike Futter (Game Informer). (2016). Review: Dead by Daylight. Article Accessed 2026-10-30. Killers with special abilities at release, such as setting bear traps.
Dead by Daylight Wiki (wiki.gg). Dead by Daylight Wiki, The Trapper. Wiki The Trapper released with the game on 14 June 2016; up to two bear traps carried, eight disarmed traps spawning around the map, armed traps immobilising and injuring survivors who step in, escape attempts or rescue by another survivor, and the Trapper caught by his own traps.

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West, James, Jr. (2026). "Trap." Game Mechanic Compendium, updated 2026-10-30. http://localhost:4321/abilities/trap

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