Traps

Traps are an important means of protecting many strongholds. They never sleep, cannot be distracted, and they don’t take bribes.

The trick here is to be judicious. Though you want to make your stronghold as safe as possible, it’s not worthwhile to have every square foot of the place trapped. People must get around it on a daily basis, after all.

If you would like to create your own traps, use the following guidelines, originally presented in Song and Silence.

Step 1: Figure out the Concept

Step 2: Determine the Trigger and Reset

Step 3: Figure out the Numbers

Step 4: Figure out the Cost

Step 5: Craft the Trap

See Below

Table 2–16: Base Cost and CR Modifiers for Mechanical Traps

Feature	Base Cost Modifier	CR Modifier
Trigger Type
Location	-	-
Proximity (mechanical)	+1,000 gp	-
Touch	-	-
Touch (attached)	–100 gp	-
Timed	+1,000 gp	-
Reset Type
No reset	–500 gp	-
Repair	–200 gp	-
Manual	-	-
Automatic	+500 gp (or 0 if used with timed trigger)	-
Bypass Type
Lock	+100 gp + 200 gp/+5 increase above 30 to Open Lock DC	-
Hidden switch	+200 gp + 200 gp/+5 increase above 25 to Search DC	-
Hidden lock	+300 gp + 200 gp/+5 increase above 30 to Open Lock DC, +200 gp/+5 increase above 25 to Search DC	-
Search DC
15 or lower	–100 gp/–1 decrease below 20	-1
16–19	–100 gp/–1 decrease below 20	-
20	-	-
21–24	+200 gp/+1 increase above 20	-
25–29	+200 gp/+1 increase above 20	+1
30+	+200 gp/+1 increase above 20	+2
Pit or Other Save-Dependent Trap
Reflex save (DC 19 or below)	–100 gp/–1 decrease below 20	–1/–5 decrease below 20
Reflex save (DC 20)	-	-
Reflex save (DC 21+)	+300 gp/+1 increase above 20	+1/+5 increase above 20
Ranged Attack Trap
Attack bonus +9 or below	–100 gp/–1 decrease below +10	–1/–5 decrease below +10
Attack bonus +10	-	–
Attack bonus +11 or higher	+200 gp/+1 increase above +10	+1/+5 increase above +10
Mighty damage	+100 gp/+1 damage (max +4)	-
Melee Attack Trap
Attack bonus +9 or below	–100 gp/–1 decrease below +10	–1/–5 decrease below +10
Attack bonus +10	–	–
Attack bonus +11 or higher	+200 gp/+1 increase above +10	+1/+5 increase above +10
Mighty damage	+100 gp/+1 damage (max +4)	-
Damage/Effect
Average damage	-	+1/7 points of average damage*
Miscellaneous Features
Alchemical device	-	Spell level of spell effect mimicked
Gas	-	-
Never-miss	+1,000 gp	-
Multiple target	-	+1 (or 0 if never-miss)
Onset delay (1 round)	-	+3
Onset delay (2 rounds)	-	+2
Onset delay (3 rounds)	-	+1
Onset delay (4+ rounds)	-	-1
Poison	-	-
Pit spikes	-	+1
Touch attack	-	+1
Water	-	+1
Extra Costs (Added to Modified Base Cost)	-	-
Poison	Cost of poison used† (×20 if automatic reset)
Alchemical device	Cost of item from Table 7–9 in the Player’s Handbook (×20 if automatic reset)

*Rounded to the nearest multiple of 7 (round up for an average that lies exactly between two numbers). For example, a trap that deals 2d8 points of damage (an average of 9 points) rounds down to 7, while one that does 3d6 points of damage (an average of 10.5) rounds up to 14.

**See Table 2–4.

†See Table 2–1.

Reset

A reset element is simply the set of conditions under which a trap becomes ready to trigger again. The available types are explained below.

No Reset: Short of completely rebuilding the trap, there’s no way to trigger it more than once. Spell traps have the no reset element.

Repair Reset: To get the trap functioning again, you must repair it.

Manual Reset: Resetting the trap requires someone to move the parts back into place. It’s the standard reset for most mechanical traps.

Automatic Reset: The trap resets itself, either immediately or after a timed interval. Magic device traps get this feature at no cost.

Bypass (Optional Element)

If you plan to move past a trap yourself, it’s a good idea to build in a bypass mechanism—something that temporarily disarms the trap. Bypass elements are typically used only with mechanical traps; spell traps usually have built-in allowances for the caster to bypass them. The check DCs given below are minimums; raising them alters the base cost as shown on Table 2–2.

Lock: A lock bypass requires an Open Lock check (DC 30) to open.

Hidden Switch: A hidden switch requires a Search check (DC 25) to locate.

Hidden Lock: A hidden lock combines the features above, requiring a Search check (DC 25) to locate and an Open Lock check (DC 30) to open.

Table 2–17: Raw Materials Cost and CR Modifiers for Magic Device Traps

Feature	Raw Material Cost Modifier*	XP Cost Modifier**	CR Modifier
Highest-level spell (one-shot)	50 gp × caster level × spell level	4 XP × caster level × spell level	Spell level or +1/7 points of average damage per round*
Highest-level spell (automatic reset)	500 gp × caster level × spell level	40 XP × caster level × spell level	Spell level or +1/7 points of average damage per round*
Alarm	-	-	-
Other spell effect (one-shot)	50 gp × caster level × spell level	4 XP × caster level × spell level	-
Other spell effect (automatic reset)	500 gp × caster level × spell level	40 XP × caster level × spell level	-
Extra Costs (Added to Raw Materials Cost)
Material Components	Cost of all material components used (×100 if automatic reset)
XP Costs	5 × XP cost (×100 if automatic reset)

*Rounded to the nearest multiple of 7 (round up for an average that lies exactly between two numbers). For example, a trap that deals 2d8 points of damage (an average of 9 points) rounds down to 7, while one that does 3d6 points of damage (an average of 10.5) rounds up to 14.

**These formulas supersede those given in the Creating Magic Traps section in Chapter 4 of the DUNGEON MASTER’s Guide.

Repairing and Resetting Mechanical Traps

Repairing a trap requires a Craft (trapmaking) check against a DC equal to the one for building it in the first place. The cost for raw materials is one-fifth of the trap’s original market price. To calculate how long it takes to fix a trap, use the same calculations you would for building it, but substitute the cost of the raw materials required for repair for the market price.

Resetting a trap usually takes only a minute or so— you have to lever the trapdoor back into place, reload the crossbow behind the wall, or push the poisoned needle back into the lock. For a trap with a more difficult reset, such as Baltoi’s boulder, the DM should set the time and manpower required.