Milling door trap

Here’s our first trial of a generic format that describes the trap first and then gives the rules information later. Both systemless and levelless, we’ll add guidelines for specific rules systems but not specific levels. We invite readers to add numbers for specific levels and/or new rules systems. 

This trap appears as – and to some extent actually is – a secret door in an apparently featureless wall, a hairline rectangular crack with a latch that can either be opened by finding and pressing a hidden pressure-pad in the centre of the “door”, slid open by a thin, rigid object passing through the crack like the old credit card trick, or pushed back by magical or psychic means.

However, the door is not hinged on the side. Instead, when the latch is released, it pivots around its bottom edge, as does the floor immediately in front of it and behind it, and a similar height of wall underneath the floor, like the blades of a river mill or a steamship’s paddle wheel. In cross-section, it is as though a + symbol rotates through 90 degrees, with the top arm of the + being the “door” and one of the horizontal arms being where the person opening the door is standing. In other words, the floor falls out from under the person opening the “door”, the “door” swings down and replaces the “floor”, and another section of “floor” on the far side of the door swings up to replace the “door”, latching firmly into place like the original “door”. This means the mechanism automatically and endlessly resets itself unless forcibly jammed while in action. Anyone who is not cleanly within or outside the trapped floor area (such as someone attempting to open the door while not standing on the loose “floor”) risks being struck by the door as it swings forwards, propelled by both the mechanism itself and the weight of whatever is on the trapped floor.

It’s up to you whether there actually is anything on the other side of the door, how deep the pit underneath the floor is, and what lies at the bottom – but note that the pit into which victims fall is sealed, and the trapdoor opens towards anyone trying to climb back up.



D&D 4e:




To spot the secret “door”

Moderate Perception

As for PFRPG

To find the latch release

Hard Perception to spot both door and mechanism, or easy Perception once door found

As for PFRPG

Accurately detect the full mechanism

Very hard Perception, or hard Perception if specifically searching floor

As for PFRPG





Release the latch

Easy Disable Device

Easy Thievery

Release the latch without triggering the door to pivot (leaving it loose to be triggered by the next person to stand on the trapped floor)

Hard Disable Device

Hard Thievery

Jamming the pivot

Any object used to jam the pivot takes 6d6 initial damage (for a Huge object) plus 1d6 per round. The initial damage can be split between two objects if the pivot is jammed from both sides.

Any object used to jam the pivot takes (Level/3)d6 initial damage, and is immobilized and takes 5 ongoing damage per tier (save ends both). The initial damage can be split between two objects if the pivot is jammed from both sides.







To avoid falling if fully within trapped area

Very hard Reflex save; failing by less than 5 gets you trapped

Trap attacks, +(Level/2+5) vs Reflex: Hit the character suffers effects listed under falling; Miss by 5 or less the character is caught instead

To avoid being caught between floor and panel if partly outside the trapped area

Hard Reflex save; failing by 5 or more means the character is hanging by their trapped limb and risks falling when freed unless they or an adjacent ally make a hard Reflex save, or an adjacent ally has a readied action to catch them.

+Level/2 vs. Reflex: Hit the target is caught (see below). If the attack hit by 5 or more, the target falls when freed unless they make a successful saving throw or an ally has an action readied to catch them.




Falling: forcible relocation to the area below

As described

As described

+ standard falling damage, plus optional extras depending on area below

1d6 per 10 ft.; see core rules or here for extras

1d6 per 10 ft.; see DMG and DMG2 for extras

Caught between floor and descending pivot

6d6, plus additional moderate Reflex save or arm is trapped; character is immobilized and takes 1d6 damage per round until freed by a DC 20 Strength check.

(Level/3+1)d6 damage, plus character is immobilized and takes 5 ongoing damage per tier (save ends both). An ally may spend a full-round action to lend their Strength bonus to the next save.

Categories: 4E, Generic, Pathfinder | Tags: , , , , , , | Leave a comment

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