Looking Over Book of Challenges: Just Passing Through

It's just cover art

This is a collection of four simple encounters in the same area, so I’ll give a breakdown of the area and each encounter individually before my final assessment.



A cavern with some natural traps serves as a stage for various encounters as the party goes through it multiple times.


Restocking dungeons after the party “clears” them is a key part of the game if moving through the same area multiple times is meant to be engaging. In doing that, it’s important to consider how that space evolves over time. This entry does both.

Making knowledge of the area’s hazards a tool that can be leveraged in future encounters is good design.

The quicksand mechanics are fairly streamlined and allow both the trapped character and their allies to take action after an initial failure. It’s a nice improvement over a basic pit trap.


The boxed text says very little and takes far too long to do so, especially when it’ll need to be followed with a description of the actual encounter(s) in the room. I’d cut it down by removing the part about not being able to see the whole space and combining the parts about natural columns and stalactites into a single point.

The history of cave-ins having shaped the area should be reflected in the present condition of the walls.

Given how “disable device” is a very abstract action in general, I don’t see the harm in letting characters come up with a way of “disabling” one of the natural pit traps by rigging something to distribute the load on it if they can find the weak spot(s) (assuming I was running a game system where rolling dice to disarm/disable a trap was an expected mechanic).

As usual, I’m not a fan of the “uneven floors […] prevent running” approach and would opt for difficult terrain with checks to do more than basic movement.


I’ve never liked the phrase “combat encounter” when it comes to TTRPGs. In my preferred way of playing, an encounter should just be an encounter, with combat being one possible avenue of approach. I’ve played in the way of having predetermined “combat encounters”, “social encounters”, “puzzle encounters”, etc. before and had fun with it, but I find it more fun when the world reacts to the PCs instead of running on scripts.

It’s impossible for “magical ranged weapons [to be] necessary” unless the encounters are forced combats where the PCs can’t retreat.

Saying that all the different creatures that use the area “know about and avoid” the various natural hazards is a contrived cop-out. Even real-world humans need to exercise caution when using things that could hurt them (hitting yourself with a hammer in a moment of complacency, bumping your head from standing or jerking on reflex in a confined space, or getting a papercut from searching through loose sheets too quickly are all common mistakes), so I see no satisfying reason why something that could set off a trap in a game should have blanket immunity to doing so.

Much of the advice under “Incorporeal Creatures in Combat” is repeating rules from the core books and thus worthless.

The advice for scaling the challenge is all over the place because it gives one big list with all the different encounters mixed together. Most of it is just about varying the number of creatures, and the three that involve combining two of encounters into a single larger one provide little-to-no guidance on the tactical implications of doing so.



Representing the delver’s protection from fighting in its tunnel as a cover bonus is a good approach.

Having information as a reward for befriending the delver is nice.

The further treasure the delver can offer over time is a decent hook to get players to return to the cavern, even if the actual treasure itself is fairly unremarkable.


I suppose the delver’s “unhinged and violent” state is supposed to justify why it resorts to violence immediately despite its intelligent behavior (demanding metal verbally). I’d have its initial tactics depend on whether someone falls in a pit (presenting as easy prey and thus inviting an ambush) or not (presenting as potentially-competent opposition, especially if the party isn’t clumped together, and thus giving reason to open with words and display while sizing them up).

The delver “fights to the death” while making demands that the PCs “might be able to [use to] negotiate with it”, except that “it won’t listen to reason” while in combat. This is a pretty classic dick move of giving the players a way to get out of a situation while doing everything to make sure the players won’t go through with it; sure, they can jump through hoops to placate the delver and then leap to the conclusion of using a heal spell to calm it down, but even in that case “the delver should attack the character who approaches it at least once” just to make them feel stupid for trying. I can understand having some hurdles so that speaking with the delver doesn’t neutralize it immediately, but this write-up is overboard.


The delver is described as “particularly large” despite having the same size category and facing/reach as a standard delver.



Incorporeal undead are a good choice for their obvious synergy with mobility-impairing physical hazards.

The write-up leaves some opening for parley, although how to go about initiating that successfully is left to the GM (which is for the best, considering what the delver’s parley write-up was like).

The “Tactics” section is simple but effective, and including a retreat condition is always welcome.


Standard Dungeons & Dragons specters have recognizable features from their former life, which I always felt was their key distinction from wraiths. While I approve of their innate hostility (which is what makes them distinct from ghosts), it’s worth thinking about who they were in life so give the players options aside from direct combat.


Given that the specters are intelligent enough to set an ambush, it doesn’t make sense that the one watching the northern entrance wouldn’t wait inside a pillar that gives a better view of it.





While the “Tactics” section mandates attacking metal at first, I think it makes sense to target whichever material (wood, stone, metal, or glass) would affect the most weapons in the area of effect.

Since their tactics don’t require any rolls to hit, the destrachans should be willing to ignore targeting armor unless they have a good reason to.

I’d normally count a retreat condition as “Good”, but waiting until there’s only one left is too late. If I wasn’t using a morale check, I’d make them flee after either two or three losses, depending on how the fight had been going for them.


There’s a possible inconsistency in the “Tactics” section; only one destrachan attacks the party’s metal equipment in a surprise round (with the others using their nerve attack), but then they use “one or two attacks against the party’s equipment” before switching to nerve attacks in subsequent rounds. Admittedly, the inconsistency depends on whether that “one or two” is taken to mean each or collectively.

The destrachans try to cause small cave-ins if they’re affected by silence, but that seems unreasonable given that being silenced or deafened is akin to blinding them.



Digging itself into regular sand and then using project image to appear trapped in quicksand is a clever set-up. It’s unlikely to work at EL 18, but it’s a fine idea for use at lower levels.

The trick of calling for help while in a room that the players know contains various hazards is great (assuming they didn’t clear out the hazards at some previous time, of course). Having the marilith get irritated if they delay in helping “her” is a nice touch, too.

The “Tactics” section gives a reasonable framework for using the marilith’s spells. The GM should be open to deviating from it, but having that as a basic tactical flowchart doesn’t hurt.

As with the other entries, having a retreat condition is welcome.


The standard 100’ range for demon telepathy doesn’t cover all of the possible entrances from the marilith’s keyed starting position, so either changing that or allowing it to be caught off-guard (and thus without its eight preparatory spells/potions) are necessary.

Given the marilith is “alert for any possible advantage in combat” and is going to some lengths to draw in the PCs, having it take hostile actions immediately when they come into view feels off. It should at least take a moment to try baiting them into compromising their formation before trying to summon other demons, particularly since the summon attempt has a 50% chance to fail.


The “tactical possibilities” of the cavern might be impactful at EL 12, but it feels like a stretch for a CR 17 demon to care so much about them that it’d use the cavern as a staging ground.

Of the marilith’s eight weapons, only one is not strictly a mathemagical item (and even saying that much depends on having a generous view of the “chaotic” tag). Of its other four non-potion magic items, only the ring of mind shielding is not about improving numbers. Its potion selection has some more interesting choices, but its equipment is boring.

While giving the marilith expensive jewelry as treasure is reasonable, giving it six copies of the exact same piece of jewelry is definitely a lame way to do it.

Repeating a summary of unholy aura’s effect is worthless.


While there’s more clear direction to these encounters than there was for Mimic Madness or for Trouble Cubed, I think this is the least useful of the three. Each of the four encounters is more or less fine, with the destrachans being the weakest and the marilith being the best, but none of them really pops out at me as something that I feel inspired to use. I’d be more likely to take ideas from the marilith’s preparations for my own encounter than to use it as written.

That said, there is good food for thought in here regarding how different creatures interact with the environment. In particular, I’m a fan of the marilith finding a hazardous room that gets “a reasonable amount of traffic” and pretending to be a Damsel in Distress with its illusions, but the others all had some nice points along these lines (the delver set up the tunnels and pits, the specters take advantage of moving through pillars, and the destrachans can drop rocks from the ceiling if their main attack is hindered). I think considering those details is an important part of making creatures feel more intelligent and/or cunning in play and giving more character to their combat actions.

All in all, the encounters here are all basically ok, but the real value in this entry is the thoughts it can inspire elsewhere. While I wouldn’t feel compelled to use any of the actual encounters, reading through them is absolutely worthwhile.


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