Trapcraft (Custom Skill)

Trapcraft is a specialized skill used to detect, design, construct, disarm, and improvise traps — both mundane and magical. Whether you're a battlefield engineer, dungeon-delving rogue, or cunning survivalist, Trapcraft reflects a character’s expertise in turning the environment and resources into deadly hazards or clever defenses.

What Trapcraft Covers

Trapcraft replaces or supplements traditional skills like Investigation, Survival, Thieves’ Tools, and even Arcana when dealing with traps. It provides a unified system for interacting with traps across all forms — mechanical, magical, alchemical, natural, or improvised.

Common Uses of Trapcraft

Detect a tripwire in an old ruin | check Wisdom (Trapcraft)

Set a concealed snare in the woods | check Dexterity (Trapcraft)

Design a collapsing hallway trap | check  Intelligence (Trapcraft)

Disarm a magical glyph etched into a statue’s base| check  Intelligence (Arcana) + Trapcraft proficiency

Improvise a shelf-collapse trap in a tavern brawl | check  Wisdom (Trapcraft) or Dexterity (Trapcraft)

Learning the Trapcraft Skill

Characters can acquire proficiency in Trapcraft through any of the following:

• Selecting a custom or modified background (e.g., Hunter, Mercenary Engineer, Wilderness Saboteur)
  
  

• Taking a custom feat (see: Trap Mastery)
  
  

• Spending downtime to train, requiring:

  • 30 days of training

  • 250 gp in materials or tutelage

  • A willing instructor proficient in Trapcraft (or narrative justification)
    
    

Using Trapcraft in Play

Trapcraft adapts based on the nature of the trap and the intended interaction. The table below outlines typical trap categories and their common ability pairings:

Mechanical

Examples: Pitfalls, spike traps, swinging blades

Common Ability Modifier: Intelligence or Dexterity

Alchemical

Examples:Acid sprayers, fire flares, smoke bombs

Common Ability Modifier: Intelligence

Natural

Examples: Logfalls, spiked pits, hidden snares

Common Ability Modifier: Wisdom or Dexterity

Magical

Examples: Glyphs, runes, arcane wards

Common Ability Modifier: Intelligence (Arcana + Trapcraft)

Improvised

Examples: Collapsing furniture, loose tiles

Common Ability Modifier: Wisdom or Dexterity

INT (Trapcraft): Design or disarm complex traps
DEX (Trapcraft): Set traps requiring precision or concealment
WIS (Trapcraft): Spot, understand, or improvise traps in nature or chaos

Setting and Detecting Traps

A Trapcraft check is used when building, spotting, disabling, or understanding traps. The DC is set by the complexity and materials involved.

Trap Difficulty Class (DC) Guidelines

Basic noise trap or hunting snare | DC 10

Standard dungeon trap | DC 15

Magical or highly advanced trap | DC 20+

Under pressure or while rushed | DC +2 to +5

Backfire Risk: On a failed Trapcraft check by 5 or more when setting a trap, the trap may misfire, trigger early, or injure the creator.

Trap Effects Examples

Snare

Restrains target; DC 13 DEX save to avoid or escape

Pitfall

1d6–4d10 bludgeoning damage, possible prone or restrained condition

Flame Jet

3d6 fire damage; DEX save for half damage

Poison Spray

2d10 poison damage; CON save for half; exposure may apply poison

Glass Tripwire

Cuts movement speed, 1d4 slashing damage and reveals position

 Traps can be crafted to deliver status effects like blinded, poisoned, or restrained, depending on materials and design.

Crafting Traps

Crafting a trap takes a combination of resources, time, and ingenuity.

Requirements

• Materials appropriate to the trap (e.g., nets, spikes, oil, glyph dust)

• Time — from 1 minute (for a crude battlefield trap) to several hours (complex design)

• Successful Trapcraft Check

Tr

Quick & Dirty 1–5 minutes
Basic mechanical 10–30 minutes

Advanced or magical 1–4 hours

🕯️ Complex traps may require ritual components, magical foci, or rare ingredients depending on their function.

Tool Proficiencies and Trapcraft

Certain tools grant advantage on Trapcraft checks when applicable to the task:

Thieves' Tools

Picking trap locks, bypassing triggers

Tinker’s Tools

Assembling gears, crossbows, mechanisms

Smith’s Tools

Crafting metal parts, blades, fittings

Poisoner’s Kit

Creating toxins or venom-based traps

Feat: Trap Mastery (Optional)

Trap Mastery
Prerequisite: Proficiency in Trapcraft

You are a consummate engineer of death and deception.

• Gain Expertise in Trapcraft (double proficiency bonus)
  
  

• You can set a prepared trap as a bonus action

• Your traps gain a +2 bonus to their save DC

• You disarm traps in half the normal time

• You reduce material costs for trap creation by 25%
  
  

DM Tips: Integrating Trapcraft

• Use Trapcraft to make trap-focused players feel impactful

• Let players build traps for ambushes, fort defense, or delaying enemies

• Don’t make every Trapcraft check binary; use degrees of success:
  
  

  • Success by 5+: Trap is harder to spot/resist

  • Fail by <5: Trap works but has a flaw

  • Fail by 5+: Trap backfires or fails entirely
    
    

Optional Rule: Trap Points

If using a trap-building system during exploration or downtime, allow players to spend Trap Points, representing creative potential or resource pools. For instance:

• 1 Trap Point = basic snare

• 3 Trap Points = advanced mechanical trap

• 5+ Trap Points = custom magical or complex contraption
  
  

This encourages planning and limits overuse without stifling creativity.