This has been a highly requested series from my patrons: a closer look at the player characters in my Dragon Heist campaign and how I (or, more accurately, we) integrated them into the game. I’ve resisted writing it, however, because I wasn’t entirely sure how to make it high-value.

The key thing is that I already wrote a couple posts about creating characters for long-term campaigns — Running the Campaign: Designing Character Backgrounds. The short summary is:

1. Establish the campaign concept.
2. Have the players pitch their character concepts.
3. Collaborate on a public integration, with the GM using their expertise in the setting to take generic archetypes of the character concept (e.g., northern barbarian) and make them specific (e.g., a member of the Tribe of the Red Elk).
4. Have the GM do a private integration of the character, tying them into the larger structure of the campaign (e.g., Is there a major villain? Make it the long-lost brother of one of the PCs).
5. Bring the party together. At least 95 times out of 100, you’ll want to explain why the PCs are all going to generally hang out and do things together — specifically, the usually crazy things the campaign concept is predicated on — before you start your first session. 4 times out of the remaining 5, you’ll probably want to have things pre-arranged so that they all fall in together within the first few scenes.

There are other ways to handle character creation, but this was essentially the same procedure I’d followed for Dragon Heist. It didn’t feel like there was really new territory to explore.

I’ve had a number of recent conversations, however, suggesting that people would like to see more practical examples of what some of this theoretical material actually looks like in actual play. So that’s our primary goal here.

I’d also commissioned some really fantastic art depicting the characters from @BroadfootLenny, so if nothing else you’ll be able to “ooooh” and “aaahh” over some pretty pictures!

THE BASELINE

Let’s start by establishing a baseline understanding of how character creation (and the campaign in general) were set up. You might want to start by reading through those two earlier posts for a more detailed discussion of the general procedure, but it’s probably not strictly necessary.

GAME SESSIONS: We should briefly discuss how we were actually playing the campaign because it has an impact on how character creation played out.

As I’ve discussed previously, we mostly played Dragon Heist in weekend intensives: We would play four hours on Friday night, then 10-12 hours on Saturday, and then another 8-10 hours on Sunday.

We also went from talking about doing this to actually doing it very quickly. This meant that, for our first weekend, we would be creating characters Friday night and then starting the campaign the next day at 10 AM.

This was unusual for me: For a dedicated campaign like this, I’m usually chatting about characters and swapping e-mails weeks ahead of time. There’s often a Session 0 with one or two weeks before we actually start play, allowing further development and refinement of the characters before we get going. In this case, all of this was truncated and there would be very little time (particularly very little awake time) between creating our characters and launching into a long-term campaign with them.

CAMPAIGN CONCEPT: My pitch for the campaign was pretty straightforward: “Would you like to play the new Dragon Heist campaign from Wizards of the Coast? I’ve been remixing it for my website.”

Although brief, this carried with it some key information:

• We were playing D&D 5^th (Just saying “D&D”, as I’ve noted in those previous essays, carries a lot of weight when it comes to campaign concept, in a way that isn’t necessarily true for other RPGs.)
• The campaign would in some way involve a “heist.”

To this, if I recall correctly, I basically added only one additional piece of information:

• The campaign will be taking place in Waterdeep, which is located in the Forgotten Realms.

I had maps of Waterdeep and Faerûn hung on the walls of our game room for handy reference. For players who were not familiar with the source material, I also briefly introduced them to the various sourcebooks we’d be using, including:

• Sword Coast Adventurer’s Guide
• 3^rd Edition Forgotten Realms Campaign Setting
• 1^st Edition Forgotten Realms boxed set
• 2^nd Edition Forgotten Realms: City System boxed set

This meant literally holding them up and saying, “These exist, feel free to flip through them if you’re looking for inspiration.” We also identified the people at the table who were familiar with the Realms and could serve as sources of expertise. Besides myself, this was Chris and Peter, both of whom were probably more well-versed in Realms lore than I was.

We also talked about our group’s familiarity with D&D, which ranged considerably. Some of us had been playing since the ‘80s. Another had played virtually no D&D whatsoever, but had just started playing in another 5^th Edition campaign a couple months earlier. Another had played one session of 2^nd Edition in 1997, one session of 3^rd Edition in 2003, and a dozen or so sessions of my OD&D open table. Personally my own experience with 5^th Edition was limited — I’d played a couple of sessions in a heavily homebrewed game and hadn’t run it at all yet.

BRINGING THE PARTY TOGETHER: The last thing I said before starting character creation was that:

• The first scene of the campaign would be the five of them walking through the doors of the Yawning Portal to meet a contact who was offering them a job.
• In creating their characters, they needed to figure out how they had ended up there.

Dragon Heist Remix – Addendum: First Impressions discusses how I handled the opening scene of the campaign in more detail, but I basically knew that this moment at the door of the Yawning Portal would bookend character creation: By immediately establishing what I needed them from them, I knew aiming at that specific moment would be hanging in the back of their brains throughout the entire process, ready to opportunistically shape any and all decisions along the way.

Then, at the end, we would return to this beat. I would show them the “Friendly Faces” handout from p. 223 of Dragon Heist and ask them to pick the picture of the NPC they were coming to meet. I knew that combining why they were walking through that door looking for a job together with who they were meeting on the other side of the door to get the job from would provide a final act of creative closure that would shape and personalize the opening of the campaign.

(Spoilers: It did.)

I think the big thing to note here is how simple this all was. I’ve talked about it at length, but it boils down:

• Four or five sentences pitching the campaign concept.
• A one sentence improv prompt for them to build their group dynamic around.
• And, later, pointing at a picture and asking a simple question.

It can be more complicated than that, but it doesn’t need to be.

In any case, that’s basically the whole set up. So now we’re going to look at the specific character backgrounds that we worked up and discuss how the procedure got us to that point.

EDANA

(Created by Sarah Holmberg)

Her father died (at least that is the story her mother told her) when she was still an infant. Her mother fell in with the Shadow Thieves as a way to make best use of her skills to support her young family. When things went south,  Edana was sent to stay with family friends while her mother worked on making plans for them to leave safely and secretly, but her mother never came back. She was told that her mother died, though she still hears rumors that make her suspect her mother is alive.

It’s part of the reason Edana tries to stay connected to, but not part of, the underworld in Waterdeep. Keeping enough distance to not make herself a target when the inevitable drumming out occurs again, but close enough to hear about her mother’s return. Though by this point, she doesn’t expect it to happen, it’s more out of habit and making best use of the skills that she picks up the occasional job from her underworld connections.

When she’s flush, she creates new personas and lives for years as them, spending her time reading, creating art, carousing,  practicing her card tricks and forgery skills. When she’s skint, she sheds those personas and returns to her true self, takes what work she can and builds up enough funds to start a new life for a while.

DESCRIPTION: Edana is a high elf with golden skin and golden hair. High, delicate cheekbones, with usually a faintly amused expression on her face. Her everyday look is hair braided back in two braids around the crown of her head, with hair loose in back. When she’s staying at the tavern she wears deceptively simple looking dresses that in blues and greens that have a lot of detail work in them. When leaving the tavern she wears breaches and a belted tunic. Her cloak has a lot of secret pockets in it.

She’s also very skilled in disguising herself. She can style her hair to cover her ears, apply makeup to make her skin look merely tanned instead of golden. She’s quick to adjust her clothing to either blend in or stand out, as needed. Even when she’s at her most broke she retains one set of very fine clothes.

WHAT EDANA KNOWS – THE ZHENTARIM:

• Zhentarim are a shadow organization of thieves, spies, assassins, and wizards that trades mercenaries and goods (including weapons) for profit.
• Their original base of power was among the Zhent people in the Moonsea region, primarily a place called Zhentil Keep.
• Long sought to gain political influence in Waterdeep, but the strength of the city’s Masked Lords, nobility, and professional guilds makes that difficult.
• In the late 14^th century (about 100 years ago), the founder of the Zhentarim (Manshoon) was killed and Zhentil Keep was razed. Zhentarim power was shattered, with the organization breaking down into many internecine factions.
• Recently the local Zhentarim in Waterdeep were rallied around a mercenary group known as the Doom Raiders. They’d been rising in power. Recently, however, there’s been a schism in the Zhentarim: A second locus of power seems to have risen within the group and is peeling support off from the Doom Raiders. You aren’t sure exactly who this second locus belongs to, but you do know that:
  • They keep an interrogation house in Brindul Alley in the Trade Ward. It was most recently being run by a woman named Avareen Windrivver.
  • Members of the new faction have taken up residence at Yellowspire, a tower in the Castle Ward.
• This schism is not widely known, because the Zhentarim are simultaneously fighting a gang war with the Xanathar Crime League.

WHAT EDANA KNOWS – THE XANATHAR CRIME LEAGUE:

• Xanathar is a beholder. He’s hundreds of years old and has held court over the Waterdhavian underworld for centuries.
• The location of his headquarters is a closely kept secret, but definitely lies somewhere under Waterdeep. Possibly in the vicinity of the underground city of Skullport.

CREATING EDANA

Sarah’s core concept was an elf with criminal connections who had been coasting for a long time. She was already playing a very young elf in another campaign, and here she really wanted to lean into elven longevity. A central image was the endless carousel of identities; each picked up, enjoyed, and then casually discarded.

In play, I think she discovered that the “safety” of Edana’s serial identities was less about comfort and more about fear. This became very interesting to explore as the events of the campaign kept pushing her to put down meaningful roots.

PUBLIC INTEGRATION: The main thing here was pulling the lore of the Shadow Thieves. Connecting the disappearance of Edana’s mother to the height of the Shadow Thieves’ power in Waterdeep (centuries earlier) helped cement just how long Edana had been coasting through her disposable identities.

PRIVATE INTEGRATION: Usually the GM’s private integration is, well, private… at least for a time. In this case, though, I immediately handed Sarah these short cheat sheets of what Edana knew about the Zhentarim and Xanathar’s gang. I framed this as being what she knew about the local criminal scene in Waterdeep, but obviously I knew both of these organizations would be featuring in the campaign. Breaking down exactly what she knew accomplished two things:

First, it let me think very carefully about what information the PCs would just know and what information would need to be discovered through play.

Second, when these topics inevitably came up during play, having the info sheet meant that Sarah could just act as an expert, using the knowledge that Edana had to brief in the other PCs. Instead of asking me what her character knew and then having the information come from the GM, she could just confidently roleplay through the moment.

It also meant that, for example, I could drop some off-hand reference to “Brindul Alley,” and then the player — just like the character — could go, “Wait a minute! I know what that means!” Which is infinitely better than me dropping an off-hand reference to “Brindul Alley” and then calling for an Intelligence check to continue telling them information. (Similar to the Matryoshka search technique.)

MAKING THE PARTY: Edana’s background obviously positioned her as a fixer, and very early on the group decided that she was probably the one who was connecting them with the contact at the Yawning Portal.

In principle, this was pretty straightforward, although it became considerably more convoluted as the other PCs became involved.

PHYSICAL DESCRIPTION: One last thing I’ll note here is how important I think it is for players to think about the physical description of their characters. I think it’s collectively essential for the whole group (and me!) to be able to picture what’s happening in the game world. I also think that the mental construct of a character’s physicality is essential for capturing the psychological gesture of the character. (If you want to delve into that, check out On the Technique of Acting by Michael Chekhov.)

The advice I’ll give for this is often very similar to that found in the Universal NPC Roleplaying Template.

Go to Part 2: Pashar

Something I’ve been asked several times since sharing the Alexandrian Remix of Dragon Heist is, “How are the PCs supposed to pull off the heist at Kolat Towers?”

The perception is that the opposition at Kolat Towers is so deadly that, if the PCs choose to engage it, they’ll get wiped out.

The first thing to understand is that, to a large extent, that’s what makes this such a great heist. The fact that the PCs can’t just bull rush their way through the opposition is both why they need to perform a heist (in order to avoid direct confrontation) and why the heist will be so utterly satisfying when they do pull it off.

With that being said, let’s talk a little bit about how this heist works in actual practice.

BROAD TOPOGRAPHY

If you’re not familiar with Dragon Heist or the Alexandrian Remix, here are a few key facts that should help you understand what follows.

(1) Kolat Towers is the headquarters for a sect of the Zhentarim ruled by Manshoon.

(2) There is a force field around Kolat Towers. Those wearing a pass-amulet can pass through the force field.

(3) You can also access Kolat Towers by means of teleportation circles that are located in various Zhentarim outposts around Waterdeep/Faerun. The Kolat Towers side of these teleportation circles are all located in a single hub at the top of one of the towers.

(4) This hub also contains a secured teleportation circle that leads to an interdimensional fortress that serves as Manshoon’s Sanctum. Using this teleportation circle requires the use of a teleportation signet ring.

(5) The primary target of the heist is a magical Eye, which Manshoon keeps in an astral vault in his library. The library is located at the top of one of the three spires in the Sanctum.

(6) Manshoon spends most of his time in his quarters or laboratory, which are more or less located at the top of the other two spires.

So, broadly speaking, you need to get access to Kolat Towers, use a teleportation signet ring to get access to the Sanctum, and then steal the Eye out of the library.

KEY FACTORS

There are a couple major factors to keep in mind when running the Kolat Towers heist.

First, as noted in the remix:

…most of the Towers’ inhabitants will simply assume that anyone who has bypassed the force field must have a pass-amulet and, therefore, must have legitimate business there. Their incredible security system has, ultimately, made them somewhat lax when it comes to actual security, and PCs who are smart enough to lean into that assumption can effectively seize a surveillance opportunity for themselves mid-heist.

This is really important. If you screw this up — by, for example, having the first NPC to see the PCs immediately scream bloody murder and call for help — then it’s going to be much, much more difficult to pull off a successful heist.

(It’s okay if the PCs screw it up, of course. That’s their unique prerogative.)

Second, the remix also has a section on “Questioning the Zhentarim” which describes what the typical Zhentarim thugs, apprentice wizards, and lieutenants all know about the layout of Kolat Towers, the location of Manshoon, the Stone of Golorr, and the location of Manshoon’s Eye.

The important thing to remember here is that all of these NPCs can (and likely will) be encountered before they enter Kolat Towers. That’s by design: If the PCs stumble blindly into a direct confrontation with Manshoon, then they’re probably screwed. To avoid that, they need to know where to go and, equally importantly, where NOT to go in the Sanctum.

Third, if things do go haywire and the heist fails, the original description of Manshoon from Dragon Heist (p. 160) should be kept in mind:

This version of Manshoon isn’t spoiling for a fight. He commends the characters for making it this far and shows no concerns for the Zhents they defeated to each him, since he considers all his followers expendable. The characters’ best chance of survival is to convince Manshoon that they can be cowed or bribed into working for him. Weary of his conflict with the Xanathar Guild, Manshoon suggests that the players prove their usefulness to him by hunting down and killing Xanathar in its lair…

I’d tweak this slightly, for the purposes of the Remix, to suggest that Manshoon’s top demand will be for the PCs to steal back the Eye that Xanathar stole from him. (Hopefully the PCs will do a better job of this new heist they’ve been pointed at.)

Regardless, at this point in the campaign it is very likely that the PCs have access to information (or people) that Manshoon dearly desires, and they should be able to trade that for their freedom and/or to form an alliance with Manshoon. This effectively gives them a mulligan on a failed heist at Kolat Towers.

THE FIRST HEIST

Let’s look at how this actually played out at my table.

One of the Zhentarim faction outposts is Yellowspire, a tower on the west side of Waterdeep used by Banite priests that contains one of the teleportation circles leading to Kolat Towers. The PCs learned of Yellowspire from their contacts in the Doom Raiders, a different sect of the Zhentarim who were opposed to Manshoon’s control.

Long story short, the PCs cleared out Yellowspire and the teleportation circle would become their access point for Kolat Towers. They also had a pass-amulet that they had obtained from raiding a different Zhentarim faction outpost.

At this point, the didn’t know much about what they would find on the other side of the teleportation circle. So they disguised themselves as Banite priests, using vestments and holy symbols gathered from Yellowspire, and went through.

Working their way down the tower from the teleportation hub, they encountered the statue of Duhlark Kolat in Area K10. They used the pass-amulet to get past the statue. (In reality, the statue simply floats into the air, issues a magic mouth challenge, and then sinks back down a minute later. But their experience was being challenged, holding up the amulet, and then watching the statue sink back down.)

Crossing to the other tower they provoked an attack from gargoyle guards and the sound of their fight attracted the attention of Yorn the Terror, a half-orc who had been trying to enjoy a little piece and quiet in the adjacent reading room with his signed copy of Volo’s Guide to Monsters.

Yorn saw their Banite robes and the pass-amulet they wore… and promptly ordered the gargoyles to stand down. “You have to show them the amulet,” he explained. “Otherwise they’re almost as big a terror as I am. Who are you here to see?”

The PCs thought quickly and offered up a basically random name that they knew to be associated with the Zhentarim: Agorn Fuoco.

I called for a Charisma (Deception) check at this point. It was a success.

“Agorn?” Yorn said. “I think you just missed him. He headed back through the portal to his quarters in the sanctum.”

“Through one of the other portals, then?” Pashar frowned.

“You came from Yellowspire?” Yorn said. “Yes. You’ll want the other teleportation circle. Do you have a signet ring?”

They did not. I could have called for a Charisma (Persuasion) test, but I decided to just let the result of the Charisma (deception) test ride forward.

“All right,” Yorn said, slipping a ring from his finger. “You can use mine. But make sure you have it back to me before dawn!”

“Pardon my ignorance,” Kora said. “But what happens if we don’t get it back before dawn?”

“I rip your arms off!” Yorn roared.

“Thank you! Much appreciated!”

Yorn gave them some brief instructions, telling them to ask Kaejva, on the other side of the teleportation circle, to give them directions to Agorn’s quarters. “And tell Agorn he owes me one.”

Yorn went back to his book, and the group rapidly backtracked to the teleportation hub.

At this point, of course, the PCs had everything they needed to smoothly access the Sanctum. And that’s exactly what they did.

THE SECOND HEIST

Ultimately, however, the first heist was not successful in retrieving the Eye: They lacked the key information of where it was located. Instead, they poked around for a bit, got a general sense of the Sanctum’s layout, and talked to a couple more Zhentarim who inadvertently told them where Manshoon’s quarters were located. Then they withdrew.

(In the process of withdrawing, they actually lured Agorn Fuoco back to Yellowspire and murdered him, too, but that has only a minimal impact on subsequent events.)

The first heist effectively became what we refer to as a “surveillance opportunity” in the heist scenario structure. They now knew a lot more information about their target, and they were going to use that to plan a second heist.

Their information, however, was incomplete. And, as a result, they drew an erroneous conclusion: They felt confident that Manshoon would be keeping the Eye on him. Thus, they believed that the target of the heist was Manshoon himself!

However, they also recognized that there was no way that they could go toe-to-toe with Manshoon, the Night King, Lord of Zhentil Keep, Master of the Black Network, and Scourge of Shadowdale.

Their solution was to go back to their contacts in the Doom Raiders — the other faction of Zhentarim in Waterdeep — and make a simple offer: “We know where Manshoon is. We have a way past his defenses. We’ll help you kill him, but you have to agree to let us take possession of a specific magical item in his possession.”

They didn’t even need to make a check for this: They’d already proven themselves to be reliable friends to the Doom Raiders, and given the circumstances there was no way that the Doom Raiders wouldn’t leap at the opportunity they were being given.

Independently I determined how long it would be before Zhentarim agents realized that Agorn Fuoco and the Yellowspire operation had been compromised. If that had happened, Manshoon’s Zhentarim would have cleared out Yellowspire, severed the teleportation circle, put Kolat Towers on high alert, and left the PCs high-and-dry. But the PCs moved quickly, and returned to Yellowspire before Manshoon’s Zhentarim realized anything was amiss.

They came with a Doom Raider strike force: Ziraj, Tashlyn, and Davil Starsong, all major leaders of the group, led a mixed force of four veterans and ten thugs. (The composition of the strike force was based on page 17 of Dragon Heist: “Tashlyn offers affordable mercenaries, either thugs costing 2 sp per day each or veterans costing 2 gp per day each.”) Yagra, the PCs’ primary contact with the Doom Raiders, also tagged along.

Their plan was simple: The PCs, once again dressed as Banite priests, would teleport through to the Sanctum. They knew from their previous visit that Kaejva, a wizard, stood watch over the arrival platform from an observation chamber off to one side. They would bluff their way past her, then circle around and kill her, before returning to usher the Doom Raider strike force through.

Here, however, their plan hit a snag: They flubbed their cover story with Kaejva and she, suspicious, prepared to cast a sending spell to summon Manshoon. One of the PCs were prepared for this however, and used misty step as a bonus action to pop into the observation chamber next to her, disrupt the casting of the spell, and throw the lever that would open the door for the other PCs.

Having killed Kaejva, they brought the Doom Raiders through.

From that point forward, their raid was basically clinical: Successful Stealth tests saw them systemically ambush and slaughter the Manshoonian zhents. (Several were sleeping. And the PCs knew where the others were likely to be congregating based on their prior surveillance.) It was overwhelming force applied to isolated, unprepared resistance.

The strike force did not, in fact, suffer a single injury before they burst into Manshoon’s private quarters.

THE DEATH OF MANSHOON

Manshoon was not so easily overwhelmed.

But what Manshoon had coming through the door at him was a platoon of twenty-four hostile warriors (including the PCs), and because there had been no warning he wasn’t prepared. He barely managed to get his robe of the archmagi wrapped around himself as the door burst open. He bought himself a few more seconds of time with a misty step followed by a wall of force, but he was pursued with misty step in kind and his concentration on the wall of force was broken. He managed to trap Davil Starsong in an imprisonment spell (the consequences of which are rather far-reaching and remain uncertain as of this writing), but then he was pretty much swallowed up by the Doom Raiders and PCs.

What’s the fall out of all this?

Well, the PCs have Manshoon’s Eye and are one step closer to restoring the Stone of Golorr. They also have his spellbook, robe of the archmagi, and staff of power. I made the decision to not limit the robe by alignment, so Pashar, the 5th level PC wizard, is glutted with power. The consequences of this, particularly with the PCs liberally spreading the word of their role in Manshoon’s death to the Harpers and Force Grey, are still to be seen.

If Davil Starsong had been around, he probably would have made a claim to these items. But with him imprisoned, the other members of the Doom Raiders who were present lacked the knowledge to push the issue. They’re fairly happy in any case: Not only did the PCs help them wipe out Manshoon, but with Manshoon dead they assisted in cleaning out the rest of Kolat Towers so that the Doom Raiders could move in. Even if/when Davil returns, he’ll probably rank “private interdimensional fortress” as a fair trade for the robe and staff.

OTHER APPROACHES

I don’t want to convey the sense that any of this is the One True Way™ for tackling Kolat Towers. Quite the opposite. The great thing about a well-designed heist scenario is that there ISN’T a One True Way™. The whole point is that the PCs are free to make their own plan and then we find out together whether or not that plan is going to work.

Honestly, even after the PCs made their alliance with the Doom Raiders I figured the most likely outcome of this plan would be that, at some point, the alarm would be raised and then Manshoon would arrive and lower the boom. It was exciting to see the plan come together and get pulled off in defiance of all expectations.

Other options that I’ve thought could work:

• Using disguise self spells to mimic the appearance of known Zhentarim agents and infiltrate the Towers.
• Actually pretend to join the Zhentarim in order to gain access to the Towers.
• Simply cut a deal with Manshoon.

What cool plan have you concocted? What have your players attempted? Did it work?

IN THE SHADOW OF THE SPIRE

Session 21: The Saint’s Schism

Liquid light in a diamond flask was brought forth. The glowing liquid was poured across Rehobath’s brow, bathing him in its light as it coursed down over his shoulders.

A circlet of elfin gold was produced and placed upon Rehobath’s brow. As it settled into place, the liquid light flowed back up across his body, becoming concentrated in a great glowing bauble that shone forth from his forehead.

About twenty years ago now, I opened a Word document on my computer and saved it as “Fantasy Materials.” It was originally intended to be a magazine article, but it quickly became the sort of project that’s never finished because it can’t be finished. The document became a storehouse for fantastical materials: Not magic items, but rather those strange substances that can only be found where pervasive magic has changed the very substance of mortal reality.

As I wrote in the introduction to the article-that-was-not-to-be:

These are not the common materials of history or the modern world. Items of marvelous grandeur may be forged from gold and silver, but such items lack the spark of the fundamentally fantastic which even a simple blade of mithril possesses. This, then, is a catalog of things which never have been and will never be. Here there are gems which will never sparkle; trees which have never been felled; stones from quarries which will never be mined; metals which will never be forged.

They are the building blocks of a world which can live only in our imagination.

Some of the material in this article was stuff I had created out of wholecloth – like taurum, the true gold which makes common gold naught but a bauble, or wave cypress, a pale blue wood that never rots. Others, following in the grand tradition of mithril, were the result of kitchen-sinking, like Terry Pratchett’s darklight or Fritz Leiber’s snow-diamonds.

This is clearly something that Monte Cook also enjoys, as the Ptolus sourcebook includes a number of unique special materials, too. (Including the liquid light referred to above.)

The utility of this storehouse is manifold:

• It’s an easy resource to tap when you want to put magic in the set dressing.
• Any time you want to infuse an element of the game world with the fantastical, you can reach for this list and do so. For example, the ritual of the novarch’s inauguration is studded with liquid light (what it says on the tin), godwood (a pale white wood that glows in the presence of divine magic), and elfin gold (an alchemical admixture of gold and ruby dust with tremendous flexibility).
• It allows you to craft structures and vistas impossible in the mundane world. For example, the lighter-than-air stone known as heliothil which makes floating towers and flying ships possible. Or the sheets of ruby crystal which can be used to create literal gemstone rooms.
• It can be used to create fantastical challenges for high level characters. Ironwood, for example, requires adamantine axes to fell and can be used to construct incredibly sturdy doors and other structures. Or locks made of cortosis that resist magical knock spells.
• It can provide memorable and noteworthy treasures (much like Bilbo’s original mithril shirt). For example, abyssopelagic gems that are fused in the depths of the ocean and melt at the pressures of sea level unless preserved with magical stasis fields. Or the lens of phantomglass that allows you perceive invisible spirits. Or the woven shirt of ghost grass which has the protective properties of chain.

It would be a mistake, though, to constantly fill your world with novel, never-before-seen material. The reason “mithril” resonates with meaning when I say it to you is because you have been exposed to it countless times; its redolent with lore. So the new fantastical materials you introduce to your campaigns will gain meaning over time as you reincorporate them into new contexts: The PCs encounter a statue of elfin gold, the individual strands of its metallic hair impossibly blowing in the wind. They see it used as magical circlet by Rehobath. They discover small craft-ingots of it in the alchemical laboratory of a dark elf. And so forth.

It’s great when the players recognize and truly know these fantastical materials. It’s even better when they’ve internalized them and start seeking them out: “You know what would be useful for this? Some shadow-veined rock.”