Magic defeats magic. This simple rule explains why trapsmiths refrain from using it in their designs. If any wizard’s apprentice can detect the trap, what is the point of using it? For instance…

Burning Hands Trap
CR 3; magic device; proximity trigger (alarm); automatic reset; spell effect (burning hands, 5th-level wizard, 5d4 fire, DC 11 Reflex save half damage); Search DC 26; Disable Device DC 26. Cost: 2,500 gp, 200 XP.

The problem with this trap is that the CR rating is off. On average this trap deals 12.5 points of damage, which is not nearly enough to rate it a CR 3 trap. This is a CR 2 trap based on that alone.

Worse, detect magic will reveal this trap, thus its only defense is the Disable Device DC of 26. That’s high enough to make this trap a nuisance, but not a threat.

Hellish Oil Mist Trap
CR 2; mechanical; proximity trigger; automatic reset; DC 15 Reflex save half damage; ignited mist of oil (4d6 fire); multiple targets (all targets in two adjacent 10-ft. squares); Search DC 24; Disable Device DC 24. Market Price: 7,200 gp.

Multiple nozzles vaporize and inject several pints worth of oil into the affected area, creating an oily mist. A heartbeat later another nozzle drips an arc of alchemist fire through the mist, igniting the area in a hellish conflagration. All who fail their Reflex save suffer 4d6 fire damage.

Imprisoning Searing Hell Trap
CR 7; mechanical; proximity trigger; automatic reset; multiple traps (four portcullis traps, improved hellish oil mist traps, acidic vapors trap); Atk +14 melee (3d6); Note: Damage applies only to those underneath the portcullis. Portcullis blocks passageway; DC 24 Reflex halves; ignited oily mist (10d6 fire); multiple targets; DC 15 Reflex halves; ignited mist of oil (6d6 fire); multiple targets; DC 15 Reflex halves; acidic vapors (4d6 acid); multiple targets; Search DC 29; Disable Device DC 24. Market Price: 80,000 gp.

The imprisoning searing hell trap takes the hellish oil mist trap to another level. When a party of tomb robbers enters a trapsmith’s territory, a rogue often scouts the way ahead and the rest of the party follows. This means that often only a rogue triggers any given trap.

By enlarging the size of the trap, all of the intruders can be targeted at once. The accompanying diagram shows where the proximity trigger of the trap is located: the red ‘T’. Once triggered, the four black iron portcullises drop down: creating areas A, B and C and igniting the area in flames. Their metal becomes covered with soot over time.

An improved hellish oil mist trap deals 10d6 fire damage to all targets in areas A, B and C (DC 24 Reflex save halves). After 2 rounds the second stage of the trap starts; this period of inactivity hopefully lures the friends of the affected targets near.

In the second stage, all targets in areas A, B and C are hit for 6d6 fire damage (DC 15 Reflex save halves). This fire burns for two rounds.

The last stage of the trap entails the cleaning process of the trap to ensure its correct functioning: A large quantity of acid is used to clean the nozzles of the trap. The resulting acidic vapors target everyone in areas A, B and C with 4d6 acid damage (DC 15 Reflex save halves). The trap is reset to its starting position 10 rounds later, and the portcullises are lifted for the next visitors.

A typical iron portcullis has hardness 10 and 60 hp. It takes a DC 25 Strength check to lift and a DC 28 Strength check to break an iron portcullis.

Like our traps? We’ll have another one next week.