Trapspringer:
Portcullis and Active Defenses

Trapspringer:
Portcullis and Active Defenses

Image of portcullisClang! The grate slams to the floor, sealing the exit — and alerting every monster in hearing distance….

Most traps are active defenses, contesting every foot of the dungeon. However, a passive defense can be a valuable deterrent as well. Two entry-level passive traps are the portcullis and the razor-wire trap, which we’ll re-design this week.

Portcullis Trap
CR 1; mechanical; location trigger; manual reset; Atk +10 melee (3d6); Search DC 20; Disable Device DC 20. Note: Damage applies only to those underneath the portcullis. Portcullis blocks passageway. Market Price: 1,400 gp.

This is an excellent trap, because it is a wolf in sheep’s clothing. Technically, this is not a CR 1 trap at all. Its average damage puts it just above the CR 1 level, and the note implies that multiple targets can be affected, which this should modify the CR accordingly.

Razor-Wire across Hallway
CR 1; mechanical; location trigger; no reset; Atk +10 melee (2d6, wire); multiple targets (first target in each of two adjacent 5-ft. squares); Search DC 22; Disable Device DC 15. Market Price: 400 gp.

Well-hidden, with high damage output, this is quite a good trap. However, for a one-shot trap it is still quite expensive. By sacrificing some durability, we can increase the lethality of this trap.

False door plus Portcullis Trap

What is a corridor with a false door and a portcullis trap? A prison cell. Place a stout wooden door on the far end of a 30 feet long corridor — but make it a false door that leads nowhere. Opening the door activates the portcullis trap. The portcullis drops down, sealing off the corridor and creating a 10 by 10 feet prison cell. Anyone caught directly under the portcullis suffers the appropriate damage.

Better yet, this trap can split the party just before a monster arrives. Would be a shame if the big tank fighter went through the portcullis door first and was trapped all alone while his companions turned to face the bigger threat…

False door plus Portcullis Trap
CR 1; mechanical; touch trigger; manual reset; Atk +10 melee (3d6); Search DC 21; Disable Device DC 20. Note: Damage applies only to those underneath the portcullis. Portcullis blocks passageway. Market Price: 1,600 gp.

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.

New Ways to String A Wire

While wire seems obvious, a few changes can turn it from a nuisance into a deadly entanglement. For instance, the most obvious change is to make it harder to see.

Well-hidden Razor-Wire across Hallway
CR 1; mechanical; location trigger; no reset; Atk +10 melee (2d6, wire); multiple targets (first target in each of two adjacent 5-ft. squares); Search DC 24; Disable Device DC 11. Market Price: 100 gp.

Less obvious perhaps is the notion that by attaching razor-wire to a slide, we can create an almost undetectable scything attack. With a little luck, that sliding wire can decapitate trespassers. After the attack the trap resets itself for another go. Replacing standard razor-wire with one set with diamond slivers enhances the cutting motion even further.

Sliding Razor-Wire across Hallway
CR 2; mechanical; location trigger; automatic reset; Atk +14 melee (2d6/x4, wire); multiple targets (first target in each of two adjacent 5-ft. squares); Search DC 24; Disable Device DC 24. Market Price: 7,800 gp.

Design notes on the Sliding Razor-Wire

Automatic reset: No longer is this trap passive and stationary, so we need an automatic reset.
Atk +14 melee (2d6/x4, wire): By increasing the attack roll we make sure that the trap will hit, and the diamond slivers in the wire result in a higher critical, further enhancing the lethality of the trap.
Damage: Averaging to 7, this gives us a CR of one.
Multiple targets: Increases the CR by one.
Search DC 24: Keeping this under the CR increasing level of 25 still ensures these traps are well hidden.
Disable Device DC 24: Likewise, these traps are meant to last.

Got a favorite trap, or have you used a trapspringer creation in your game? Let us know in comments!

11 thoughts on “Trapspringer: <br />Portcullis and Active Defenses”

  1. Cruel is the gelatinous cube halfway down a spiked pit trap that Monte Cook described at PaizoCon this past weekened.

    Character falls in, hits cube, is paralyzed and digested. Other PCs nail the cube, kill it — and then the paralyzed character continues his fall…

  2. It is quite the nasty trap. Monte said he enjoys traps that work in two stages:

    1) “Oh, no, it’s a trap!” and
    2) “Things just got so much worse!”

    I have to admit it’s a great way to keep traps from being just a way to tick off some resources. Combining traps with monsters seems like a good way to put the fear factor into them.

  3. “Search DC 24: Keeping this under the CR increasing level of 25…”

    I love bastard-traps as much as the next guy, but I hate it when designers go out of their way to make a challenge that is “technically CR X” (but is actually more difficult).

    Formulas for determining challenge rating are shaky to begin with. Breaking them is not an achievement. Please try to work with rather than against the CR system whenever possible.

  4. Hydro,

    true, breaking the rules is not an achievement but I honestly believe that this trap is not broken. I have done a few that obviously are and those come with a big warning sign.

    I was actually aiming for a CR 1 rating but mechanicly that went awry. So the trap became CR 2, a high end CR 2 but still CR 2.

  5. Even with search and disable DCs both in the mid 20s? Well, fair enough then.

    It wasn’t your judgement that I was calling into question (I think you’re a lot better at this than I am, actually).

    A lot of DMs and designers like to “game” CR or EL formulas to produce bastardly encounters with disproportionately low CRs, which I think is misleading to the casual dm. But if you really think CR2 is the best approximation then I appologize for the finger-wag. =)

  6. The false door/portcullis trap is one of my favorites.I once had a more exotic version combining a wall of stone trap with a false door and a dozen hidden pipes spewing seawater into the space created. Beautiful memories!

    Love the work Maurice.

  7. Thank you Phil.

    I did a few water hazards in April, but I’ve got a new water trap lurking in Wolfgang’s inbox.

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