D&D Dungeon Postmortem: Thanar’s Ruin

We just finished a pretty important side-quest in my D&D campaign and the session went really well, so I want to talk about some of the things that I did to prepare for it and how it all worked out. Special thanks go to Stands-in-Fire, who normally plays in this campaign but is still out on new-baby hiatus. He was instrumental in planning and building the main battlefield of the adventure.


This was a two-session adventure, and two of the players from the first session couldn’t make the second, so I had to write them out rather abruptly. The full party:

  • Esteban Ortega, a 4th level human thief. Ever since getting killed by the backlash of a necromantic rite, he has owed the Nightwalker a debt for allowing his resurrection to take place. The point of this quest is to pay that debt by recovering the Nightwalker’s Fingerbones.
    • The Nightwalker is a non-deific Power that currently has great power in the Ghostlands (which might as well be the Shadowfell). The main thing to know is that the Nightwalker is bent on gathering the parts of its physical body so that it can incarnate into the living world.
  • Ileskku Tiorka, a 4th level beruch warlock dedicated to the Archfey. She outright worships Verenestra.
  • Simon Barry, a 3rd level human seeker (mystic gunslinger). He is disturbingly interested in, even dedicated to, the Nightwalker.
  • Vorcrech, a 4th level veytikka cleric of Life. Though diametrically opposed to the Nightwalker, he’s willing to help his ally Esteban. Vorcrech missed the second session.
  • Mea Cellini, a human fighter with my homebrewed Enforcer background. She’s the party’s tank… and she’s 1st level at the start of the adventure.
  • Sergio Silvergate, a kagandi rogue who also has the Enforcer background. He’s also 1st level at the start of the adventure.
  • Calder Snowghost, a human ranger Folk Hero, headed for my Lantern-bearer archetype. He too is 1st level at the start of the adventure. Calder missed the second session.

It’s early winter, but the Nightwalker has made it clear, through the two telepathic ravens that follow Esteban wherever he goes, that this quest needs to get solved soon, sooner, soonest. With a lot of financial help from the mercenary company, he hires a ship to take the party from their temperate southern coastal city to the bitter, frozen domain of Kaldeshar. By coincidence*, this is where Calder is from, so he agrees to be their guide. They sail north as winter sets in around them, and they question the decisions that have brought them to this place in their lives.

* Less coincidence, more “easy in for the player, easy expository mouthpiece for the DM, what a win!”

They get attacked by strange, water-walking monsters on their way north, which proves to be a hard-fought battle for the seven of them. I declare that the 1st-level characters advance to 2nd, and a lot more in-game time passes. They see other unusual but not obviously relevant things along the way, and finally reach the only open port in the whole domain of Kaldeshar after a month or so of sailing. It is nearly the new year when they arrive.
Calder explains a bit about the politics, geography, and so on of Kaldeshar. The average Kaldesharan has a pretty good idea where the Fingerbones are: a place called Thanar’s Ruin that regularly creates undead that wander out and attack farms and villages. A Marquess rules Kaldeshar, and in the port the party learns that she is organizing a journey into the wilds despite the onset of winter. She leaves the city the day after they do.
Which means, of course, that the PCs encounter the Marquess and her entourage near Thanar’s Ruin, where they learn through various means that she is planning to sacrifice someone of royal blood to Rathmorvan, a Highlord of the Fey who is nominally allied with Verenestra; Rathmorvan will use that power to oppose the Nightwalker. The PCs spend about two hours debating what to do, eventually deciding to sneak past the Marquess’s encampment and complete their mission. The session ends when they encounter two empty suits of armor that draw swords and attack.

Session 40: Thanar’s Ruin

I had decided that I really wanted to wow them with this one and try some things I hadn’t ever done before. The core of my concept was to create terrain for an area that the PCs could explore at length, with a lot of vertical movement, and maybe a giant skeleton. I felt like building the whole thing into a large cardboard box would be really nice for transporting it, and I was satisfied to make it a narrow box canyon. 

Let me emphasize that I am not a terrain builder or wargamer. If you are, I am well aware that this won’t be up to your standards, but I was working within my own limited skillset, and knew there was a chance the players would see this once and never use it again.

I went to a nearby Michaels and looked for interesting materials. I bought a bunch of styrofoam. (This is not all of it, as you’ll see.)

I had an idea that I would cut one piece of styrofoam to make two “towers” (shown above). I also cut longer sheets of foam into smaller sections and glued them together to form a multi-level tower. 

I glued craft foam to the styrofoam, and painted the craft foam gray. I made the tower’s stories very tall so that our not-to-scale hands could move minis around inside. Despite my efforts to make the tower’s legs the same length, it didn’t wind up terribly stable, but then I also didn’t try to glue it down, and it was Good Enough. I also drew on staircases with a Sharpie.

Still, this involved a lot of styrofoam for one little tower. This was not a good method for realizing my vision, unless I wanted to spend a lot more money on styrofoam. (I did not.) This is where Stands-in-Fire comes in. He suggested using a different material: foamboard, which will be familiar to every who has ever made a science fair triptych. For the legs of the towers, he suggested using dowels. So we did.

These I likewise painted gray on the player-facing surface. We made them partially one layer (two stories tall, as Americans count floors) and partially two layers, as you see. The point, of course, was to encourage more vertical movement.

Finally, I still had this styrofoam cone, which we cut in half… but it didn’t look all that great as towers. I wanted to get something out of it, though – this piece was as expensive as about half of the rest of the project put together. So I cut a sliver more from the broader piece and glued craft foam to it, onto which I painted a door and two runes, in red. I wasn’t 100% sure what the mechanic was going to be here, but I figured I’d come up with it at the table.

(In this image, all hell has already broken loose and the PCs are pretty sure they are doomed.)

I started buying all of this stuff right around Halloween, and I had also picked up a little purple light, figuring that a little purple light would surely prove to have some interesting use. (It did.)

So what actually happened? It went down like this…

The seven of them (with me playing Calder and Vorcrech as NPCs) fought the two empty suits of armor, which were Helmed Horrors. They claimed one empty suit of plate armor after the fight and put Mea in it, over some protestations. They figured out that she would be well-protected (and immune to fireball, for that matter, because Helmed Horrors) as long as she didn’t die. The Helmed Horrors were reforming at their original positions, and the armor would eventually return to them. It really meant the 2nd-level fighter got some really badass gear that I wasn’t expecting, but only for the duration of this adventure. Note to self: Do this more often.

As they continued into the valley, Calder and Vorcrech realized that they couldn’t go forward because of their capacity for healing magic. This effect was invented on the fly to explain why they had to stay behind, though the PCs could (and did) retreat back to them for a short rest and healing spells.

As I said, we built the towers with an eye toward ease of use. I explained to the players as they approached that the towers had lots of gaps in their walls, but weren’t completely gone, so ranged attacks that crossed where a tower wall should be would have half cover or three-quarters cover, depending on what seemed reasonable. The top floor of any structure was clear and provided cover only based on angle of fire.

I also described the ground and all of the stone floors of the towers as being covered in dust and old bones, with some recognizable items from previous adventurers.

The ruins didn’t have a huge number of skeletons in any one area, but there were skeletons in almost every area. There was also a massive, 25-foot-tall skeleton in the courtyard between several of the towers – back where the purple light is in the top-down view. The skeletons weren’t coordinated to attack them, but attacked whenever the PCs got their attention. I was trying to get across that there wasn’t a single intelligence controlling them, only some very general malice-toward-the-living motivation. They cleared the three freestanding towers and started examining the red door. With detect magic and identify rituals, they determined that they needed to activate each of the glowing runes separately to cause the door to open. They immediately activated one by touching it.

I had had some notion that they would finish exploring the ruin before doing this, but they were sufficiently deterred by the idea of getting close to the giant skeleton that they wanted to accomplish as much as they could without getting closer. Activating the rune caused some of the more recent damage to the towers to be mended, and formed another half-dozen or so skeletons from the bones and dust, including one massive skeleton that had no legs, but was carried on the backs of three smaller skeletons. (Stat-wise, this was a Minotaur Skeleton without the Gore ability.) Oh, and two specters (stripped of their immunity to necrotic damage, because I wanted the warlock to have fun, instead of… not; also they had giant piles of extra hit points) appeared on the tops of two towers, hurling necrotic energy at the PCs. I think it’s fair to say that at this point they thought they were screwed and not getting out of this alive.

They fought like men and women possessed. Sergio fell to a necrotic bolt from a specter and took a failed death save from a second bolt. It looked for a moment like this might create a cascading defeat for the party, but Ileskku spared the dying (Pact of the Tome and beruch means she has a zillion cantrips) and Mea fed him a healing potion and deflected a lot of necrotic bolts from the specters. Ileskku and Simon took up the defense, giving Sergio, Esteban, and Mea a chance to escape. Between being 4th level and having 18 Con, Ileskku is one of the toughest characters in the whole company, and she gritted her teeth through several more necrotic bolts. Eventually they took down the two specters and withdrew.

It turns out that one prayer of healing from Vorcrech was good for what ailed them. They took a short rest and discussed strategy, but by this point it was already getting a little late. We’d been playing for something like five hours; they had about three hours of real time left to finish up, and they didn’t yet know everything they needed to do. Sergio and Mea received their (fairly arbitrary) XP rewards to date, boosting them from 2nd to 3rd. (They had similarly leveled from 1st to 2nd in the session prior.)

They returned to Thanar’s Ruin. Esteban and Simon sneaked up to the taller cylindrical tower, where there had been a skeleton with a starlock pistol – but more importantly, there had been a skeleton with bullets, because Simon’s ammo was running dangerously low. They tried to activate the other glyph on the crimson door, but discovered that it couldn’t be activated until something more was done to complete the first. I took this opportunity to remind them of areas they hadn’t yet explored, since there were map elements they couldn’t see from the ground and I had, therefore, not drawn in.

If you have two rogues in a party, of course you solve your problems with stealth. Esteban and Sergio each take one of the three-story towers and climb to the top, and each find a magical sigil engraved in the top. Sergio’s is glowing red, while Esteban’s (which is uncomfortably close to the giant skeleton) does not glow at all. Sergio bends down to examine it, and it paralyzes him. He stays paralyzed until he finally passes a Con saving throw, taking some damage along the way. When he does pass a Con save, a red glow remains in his grasp, and he runs it down to the glyphs by the door. Esteban’s sigil tries to extract his blood, and he declines to allow it to continue.

All the while, the other three have been fighting a few skeletons whose notice they drew. Sergio pressed the red glow in his hand into the glyph by the door, and excitement got the better of him – he immediately activated the second glyph, and still more skeletons and specters rose from the earth, including the various floors of the towers. The fighting right by the door soon grows tolerably hot, and Ileskku breaks out a suggestion on one of the skeletons. She asks it to walk back to a sarcophagus that they spotted in one of the towers on the back wall of the canyon and bring her anything of value inside. It walks away and she turns her attention to other enemies, all the while maintaining her Concentration.

Esteban and Simon finally sneak back into the round tower next to the giant skeleton. All the while, I’ve been describing the giant skeleton as bathed in a purple aura. With his Forbidden Lore class feature, Simon studies it and determines that the purple aura sustains it and grants it regeneration by flooding it with necromantic power. When they get to the top of the tower, Simon allows the glyph to take his blood, resisting some of the damage. This strips the giant skeleton of its regeneration, and it begins to falter. They abandon stealth and bolt for the stairs; it swings its hammer once and the wall of the tower explodes inward. Esteban is injured but okay. Simon is struck full force, but manages an amazing shot through the chaos, damaging the giant skeleton. Simon falls unconscious. Esteban drags him out of the tower and back to the rest of the team. Moments later, the smashed tower collapses upon the giant skeleton, burying it under half a ton of rubble.

In original design, weakening the giant skeleton would have required 1-3 more steps of deactivating defenses. In practice, it was almost time for the session to be over.

Mea, Ileskku, and Sergio are still fighting by the door against a specter and several skeletons. Ileskku takes a hit from the specter that nearly disrupts her Concentration, but thanks to Inspiration, she toughs it out. Moments later, the skeleton returns with a beating heart in hand, gives it to Ileskku, and (as the spell abruptly ends) tries to stab her. The team cleans up the rest of the active enemies, though they can still see unaware enemies in the more distant towers.
Ileskku identifies the heart and determines that someone needs to eat it to pass through the red door – which is, in fact, made of blood. This is Esteban’s quest and his problem to take on, so he asks them to look away while he does what is necessary. His jaw unexpectedly unhinges and he swallows it whole. The ravens on his shoulder abruptly die and crumble to dust. A moment later, he steps through the door of blood, and finds a pile of oddly-marked tiles, a scrap of parchment, and the Nightwalker’s Fingerbones. When he emerges from the small chamber again, he closes his hand around the Fingerbones and they vanish, returned to their dread owner. Here ends the session.


It’s really unusual that I run what was basically four separate, consecutive fights in a session, even with seven or more hours to play. It was an interesting experience. Once we had the walkways from tower to tower in the back, I was really counting on the PCs to go to those towers so that the giant skeleton could smash the walkways they were on whenever it missed. I also wanted them to maneuver for position so they could set up devastating shots on the giant skeleton. The image of the skeleton’s massive hammer making it rain rubble was central to my planning, but only happened once in play. In brief, I had ideas for yet another full session continuing in the same combat, but didn’t get to it – and it doesn’t matter because the players never knew until reading this right now.

Here are some things that worked really well:

  • Ending the previous session with a fight about to happen was all to the good, as it focused attention right from the start.
  • The big box that was terrain as well as holding terrain was good for intriguing them – they’re used to a mix of theater of the mind and TacTiles with miniatures. As you see from the images, there were no grids on the terrain here, just my best guesses of what 30 feet should be on the map.
  • There were enough rounds of combat going on, and the scene was (I think) set well enough by other things going on, that it didn’t matter that combat had almost no description of hits and misses. I’d have been repeating myself to a distressing degree if I’d tried to describe every cut and thrust.
  • Mea’s short-term armor upgrade was useful, while also increasing the tension for her personally.
  • Simon’s ammo shortage turned out to be useful, as it got the PCs to care about reaching areas of the map where skeletal pistoleers and musketeers had fallen.
  • The skeleton stats of the book are just right for low-level rogues to potentially kill in one hit, thanks to Sneak Attack damage. Esteban’s player commented on feeling great whenever he pulled off a one-hit kill.
    • On which note, an encounter like this would have been pretty miserable for those rogues in 3.x. I don’t miss undead being immune to a class’s primary damage mechanic.
  • The fact that the PCs had very limited healing resources and no idea how much more they might need to endure meant that they focused on gaining cover more than usual. Caring about cover creates a feeling of desperation in itself, I think.
    • As a result, when they broke cover to do something, it felt more significant and awesome.
  • Ileskku’s suggestion turned out to be a clever and fun way to solve the last major problem, but even if it hadn’t given them the heart they didn’t know they needed, it was a good way to keep that skeleton off her for long enough to do something about all of the other threats.

Things I could have done better:

  • I mostly forgot to take lighting issues into consideration, which meant that fighting at night didn’t mean much.
  • I probably could have done more to lure them into exploring the other areas of the ruins, but I didn’t have much more prepped for that, so it would have been 100% ad-libbing. My ad-lib DMing is pretty good, but still.
  • The adventure was lighter on treasure than I really intended, but in my defense a fair bit of the further exploration probably would have involved treasure. They got a small pouch of coinage and a magical bracelet, and they got Esteban out of the Nightwalker’s debt, so that’s not too bad.
  • I wish I could have fit a few more encounters into the session before this one – I feel like I undersold the dangers of the Kaldesharan wilderness in the dead of winter.
  • I would have liked to have inserted a non-combat challenge somewhere in the flow of the session, just to let characters use other abilities, but that’s more a matter of principle than specific need.
  • I meant to cut down the other three sides of the box a bit to make visibility easier for players seated behind it, but I would have had a harder time transporting it if I had done so. I could have cut it down at the session, but… I didn’t. As a result, two or three of the players had to move around the gaming area a bit to get a view. This was not a dealbreaker.

Useful pieces for other DMs:

  • Player handouts such as the tiles are always a big hit, especially if they are a puzzle in themselves.
  • If you have an encounter designer as talented as Stands-in-Fire that you can describe the scene and its challenges to beforehand, or even if you don’t, just saying it out loud in some kind of logical order will help you find areas that you have left vague or that don’t make sense.
  • Bounded accuracy does achieve the advertised goal: a horde of low-level creatures is a mightily useful threat.
  • Showing PCs the threats that they might have to engage later plants the seed of dread, which flowers on its own even when they’re not actively thinking about it. In this case, they were reminded every time they looked at the terrain.
  • Large numbers of low-end opponents are great in 5e. All hail bounded accuracy!
  • The giant skeleton did not have “real” stats like everything else did. I would have created an ad-hoc set of values if needed, but it never came up. If they had tried to engage it directly without breaking its regeneration effect, it would have murdered them very quickly.

I hope you’ve enjoyed this session postmortem, and possibly even found some new ideas for your own game! Thanks as always go to my players, who make the game work by engaging enthusiastically with the setting, the narrative, and their characters.

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