In the adventure Critical Role: Call of the Netherdeep, characters are bound to come across the otherworldly material known as ruidium. This alien mineral imbues its twisted energy into things it touches. While it isn’t guaranteed when the players will first encounter ruidium, one thing is for sure: its discovery will present their characters with unique challenges.
The full extent of ruidium’s role in Call of the Netherdeep is still under wraps, but let’s take a look at what we know about it and its double-edged potential. Players beware, spoilers for Call of the Netherdeep lie ahead!
What is ruidium?
Ruidium is described as a “slick, oily stone veined with blood-like streaks” that forms in crystalline structures that run through the sunken caverns of the Netherdeep. This mineral got its name from its similarities in color to the second Exandrian moon, Ruidus.
Not much is known about ruidium beyond that it is powerfully magical. Since its discovery, different scholarly factions have been at odds trying to secure a steady supply for research.
Ruidium’s properties are yet to be fully realized, but initial research of the mineral shows it can spread its crystalline structure into both organic and inorganic substances. The chances of spread are greatly increased when creatures or objects remain in prolonged contact with it.
Ruidium items
Magical items can be infused with ruidium to become even more powerful, and even mundane items develop magical properties after sufficient exposure. It goes without saying that the scholarly factions investigating ruidium would have great use for a party of adventurers that are able to get a hold of ruidium items.
While ruidium might seem like an obvious blessing from the mysterious realm of the Netherdeep, ruidium items do not come without their downsides. When used for too long, items that have been infused by ruidium spread their crystalline structure to the creatures that wield them. This process, called ruidium corruption, starts with physical effects but can also cause psychological distress in cases that have progressed beyond the initial stages.
How ruidium corruption works
The first physical sign of ruidium corruption is a bright red rash that appears on the creature’s body where it made contact with the ruidium. Due to its debilitating effects on a creature’s body, ruidium exposure also causes creatures to gain levels of exhaustion.
Creatures that are exposed to ruidium multiple times show increasingly serious symptoms of ruidium corruption, coinciding with the creature’s level of exhaustion:
Exhaustion Level |
Physical Signs |
1 |
A red rash appears, originating from the point of contact with ruidium. |
2 |
Pulsing crimson veins spread across the creature’s skin. |
3 |
Crimson blisters and boils appear on the creature’s skin. |
4 |
Stubby spurs of ruidium crystal protrude from the creature’s body. |
5 |
The creature’s crystal protrusions grow larger and more grotesque. |
6 |
The corruption kills the creature. |
Source: Call of the Netherdeep
Roleplaying ruidium corruption
While minor physical characteristics might be easy to ignore, ruidium corruption can also twist a creature's mind. A creature experiencing ruidium corruption may display signs of emotional distress that progressively worsen as the corruption spreads. The psychological symptoms of ruidium corruption include increased feelings of regret, yearning, rage, and despair.
When a character gains a level of ruidium corruption, it can be helpful for the Dungeon Master and player to decide how this will affect the character. A couple examples to roleplay ruidium corruption could be:
- Adding a flaw to the character’s flaws
- Emphasizing or expanding upon a current flaw
Curing ruidium corruption
Characters exposed to ruidium may seek to remedy themselves of this body and mind-altering substance. Unfortunately, there is no known cure beyond a wish spell or divine intervention.
While this may seem bleak for characters that have advanced ruidium corruption, there is one upside–ruidium corruption only progresses with exhaustion levels. Taking a couple of days off to get some long rests can cure a character of their exhaustion and buy them some time to discover a cure. Keep in mind that the physical and mental characteristics of ruidium corruption remain even when the exhaustion is cured.
Homebrewing ruidium cures
Dungeon Masters can find themselves in a tricky spot when multiple party members develop advanced cases of ruidium corruption. If you’re having trouble balancing ruidium corruption at your table, consider the following ideas:
- A powerful cleric may be able to help those with ruidium corruption by seeking a deity's help on behalf of a corrupted character. This service can be acquired by a sufficient donation to the church, or by the party performing an adequate favor.
- A scholarly faction, like the Library of the Cobalt Soul, may be able to formulate a cure or way to suppress the effects of ruidium corruption if the party is in good standing with the organization.
- Instead of exhaustion, characters could sacrifice other resources to keep ruidium corruption at bay. For spellcasters, this might come in the form of spell slots. Martial characters, on the other hand, might sacrifice some of their Constitution score.
Magic item preview: Ring of red fury
Below is a look at the ruidium item ring of red fury from Critical Role: Call of the Netherdeep.
Ring of Red Fury
Very rare (requires attunement)
This ring has a stripe of ruidium running through it. While wearing the ring, you gain the following benefits:
- You can breathe water.
- You gain a swimming speed equal to your walking speed.
Ruidium Rage. As a bonus action, you can use the ring to gain the following benefits, which last for 1 minute or until you are incapacitated:
- You have advantage on Strength checks and Strength saving throws.
- When you hit with an attack, you can add your proficiency bonus to the damage roll.
- Difficult terrain doesn’t cost you extra movement, and you are immune to the paralyzed and restrained conditions.
You can’t use this property of the ring again until you finish a long rest.
Ruidium Corruption. When you use the Ruidium Rage property of the ring, you must make a DC 20 Charisma saving throw. On a failed save, you gain 1 level of exhaustion. If you are not already suffering from ruidium corruption, you become corrupted when you fail this save.
Source: Call of the Netherdeep
Fighters and monks, who can make more attacks per round than any other class, will make especially good use of this item by adding their proficiency bonus to each damage roll. The one downside for those classes is that they would be particularly susceptible to failing the Charisma saving throw and gaining a level of exhaustion and exposing themselves to ruidium corruption.
A warlock, on the other hand, will be able to use this item in conjunction with their eldritch blast to pump out a lot of damage. Seeing as they get proficiency with Charisma saving throws and will most likely have a high Charisma modifier, the Charisma saving throw will be a lot less scary than for other classes.
Will ruidium bring you glory or ruin?
Critical Role: Call of the Netherdeep will set adventurers against all sorts of challenges and creatures. Ruidium may be your best chance to combat these perils, but at what cost? You can find out when the adventure drops on March 15!
Mike Bernier (@arcane_eye) is the founder of Arcane Eye, a site focused on providing useful tips and tricks to all those involved in the world of D&D. Outside of writing for Arcane Eye, Mike spends most of his time playing games, hiking with his girlfriend, and tending the veritable jungle of houseplants that have invaded his house.
I don't know about your party, but I can think of a few character's I've made who would salivate for the ring (most of them being *extremely* dumb/unwise); corruption be damned. Evil items can be a blast for roleplaying
Am I the only person tired of seeing "there is no known cure beyond a wish spell"? Why isn't there a higher level Greater Restoration? Greaterer Restoration? GOAT Restoration?
Having Obi-Wish Kenobi be our only hope is just boring, over-used, sad, pathetic, and disappointing. It's the meatloaf of gaming tropes.
Sounds like lyrium from Dragon Age.
is it just me or is anyone else irritated by the fact that unlike every other setting this one gets its own full campagin? everything else seems to just have a source book and an intro adventure and then they aren't messed with again. it seems very unfair to people who care about other settings like ebberon, theros or any other place but the forgotten realms.
Squeaky wheel gets the grease. Though for Eberron, Keith Baker has a lot material available at Dungeons Masters Guild. Then add it here as private homebrew if you want.
Very similar to Delirium from Dungeons of Drakkenheim
the corruption system suck I don't know why you'd ever think about adding that trash in a game
since there is no cure what's the point? you'r gonna bother a god or give away all the loot you find just to stave off the effect?
resting only take the exhaustion away not the flaws in the end you'r gonna play a character that is no longer your character with all the mental flaw you'r gonna add
that's why nobody play the tomb of annihilation in the end you got a character that's not the same sex or specy anymore and is mentally reformed that kind of world building is the most toxic ever
is it because mind control got people whinning that it took player agency away? their kink of controlling people got blocked so they decide to pull this? seriously?
Red lyrium from DA2 and DA:I to be specific. It's pretty much exactly that.
I feel like the drawback of the ring isn't enough. You can only use the rage once per long rest, and the corruption applies with levels of exhaustion. The ring doesn't say that you can't gain the benefits of a long rest. So essentially as long as you aren't taking more than one level of exhaustion, then you can use this indefinitely suffering no consequences as long as you treat this like a once a day usage. Sure you can technically kill you're character, but you would have to really GO OUT of you're way to ever make that happen. In fact, I would imagine that 99% of players would never even see more than the 3rd level of drawback on the ring even in the most dire circumstances, let alone the final one. I feel like the "theme" that the designer of this item was going for was some sort of "noble sacrifice" item that you would be forced to use throughout a dungeon or big story changing fight that would end up exacting a terrible toll on the user. But with a long rest as the reset for both the rage ability and for exhaustion it just kinda presents the facade of any actual potential drawbacks. I would personally design this to say that either you can use the rage once per short rest (since it only lasts 1 minute, a.k.a one encounter) or that the exhaustion levels from the ring can't simply be yeeted away with a long rest. perhaps a full 24 hrs bed rest instead or something.
The last paragraph of the article says "Ruidium may be your best chance to combat these perils, but at what cost?" It may not be the only way, but sounds like it may be extremely difficult with out it.
There is also a whole section on homebrewing cures for this, incase it does become too much for your players. Honestly I'd consider homebrewing something that can take like one level of contamination away, and recharges under both moons (I'm guessing that would be like once a month that it could recharge, otherwise find something like that that severely limits the recharge, so they must carefully select when they use rudium based magic items.
I'd also make sure they know that this is a difficult campaign, with magic that can change you, monsters that are on the horror side, and pretty intense.
Don't know if you watch critical role, but I've seen more then one instance in campaigns and one shots where a charecter was changed by a magic item. They went all in, had a blast, and it was hilarious. Travis' new charecter is based on one that had that happen.
I imagine if you wanted you could play this without rudium, you'd have to find ways to buff the charecters. Or you could help encourage your group to team up with the rivals, and have them use the rudium (though that might make them stronger then your party which the players might not like). At least then they'd see what it does before choosing to use it.
It does say that there is no KNOWN cure beyond divine intervention or wish spell, not that there isn't any other way to cure it, they even go on to say this:
Homebrewing ruidium cures
Dungeon Masters can find themselves in a tricky spot when multiple party members develop advanced cases of ruidium corruption. If you’re having trouble balancing ruidium corruption at your table, consider the following ideas:
Yeah, I watch Critical Role but most of my players don't. I probably wouldn't enjoy playing with Matt Mercer DMing. We're kind of old school (which is to say we've had PCs die in Tomb of Horrors when it first came out) and nobody wants their characters modified without consent. So, I'd have to work out a ready cure and so forth which really takes the point out of having ruidium in the game.
It literally gives 3 examples of ways it could be cured in a game. I suspect there might be a cure in the book but they aren't going to give everything away in this article.
I know! I immediately thought of that. I was wondering if there would be any kind of legal implication given that Dungeons of Drakkenheim is now an officially published third-party adventure.
I was just about to say that! I was actually thinking that one got the idea for from the other, but I'm not sure which had it first. I'm thinking Drakkenheim, just because of how well it integrates with Monty's world building. What do you think? I've actually put something like this in my post-apocalyptic home-brew setting, but I know that I was inspired to make that setting by watching Drakkenheim.
I couldn't begin to hypothesize about which campaign world was being created first, as I'm also not a (current) watcher of Critical Role, so I'm not sure if one did happen prior to the other. There have been countless examples of convergent discovery of ideas, evolution among those. I think there's space for both groups to play with the same idea; my fear, because humans be humans, is that they similarity will be viewed as a threat and action will be taken, most likely, I'd imagine, against the Dungeon Dudes. But I hope that everyone can just share the space and recognize that the concept itself, of a foreign material being introduced to a landscape with unknowable and disastrous consequences, is a great story driver. Best of luck on your campaign - I bet it's really fun creating rules about the science behind a foreign element :) I'll need to consider it myself in the future!
If your players are fully aware of the benefits and drawbacks of ruidium, there's no surprise or removal of agency. It's not supposed to be a "gotcha" mechanic, it's a risk/reward mechanic.
I mean, Lyrium in Dragon Age was a cool element, but it's hardly original to that either.
There have been examples of such things in fantasy for years, though I can't for the life of me remember some of the older ones off the top of my head. It's definitely been a theme in various Final Fantasy games and other jRPGs that predate Dragon Age, it's probably featured in D&D before then as well, and I remember reading a book from decades ago that was a definite inspiration for some of the Warhammer lore with dark (as in bloody murder) elves, chaos vs. order and other elements which feature some kind of spreading corruptions, though I can't remember the name of it (Update: Elric of Melniboné, thanks Puffe86)!
The idea of corruption having a real physical presence in the form of lyrium, ruidium, chardalyn etc. is definitely not original, it's existed for a long time; I'd wager the idea has existed in folk tales and other very old fiction as well, probably inspired by radioactive or otherwise toxic elements and such before people knew what they were.
I notice a lot of complaints about the lack of a cure and the corruption mechanic of ruidium. But I think that's the point, since Call of the Netherdeep is clearly leaning into cosmic horror. It's basically a nicer version of Call of Cthulhu. It seems like something like ruidium is clearly some old one, eldritch type of material. It's powerful, but definitely has a cost.Most importantly, the PCs most likely won't know about it. They might see a magical ring that offers cool abilities. Why wouldn't they attune to it, unless they knew the drawbacks.
In a game with cosmic horror (Call of Chtulhu fans will get it), your character are meant to struggle. Cosmic horror gets dark. Your characters will feel helpless and do the best to hold onto their sanity. Sometimes, ultimate demise is inevitable. The moon wins.
Of course, a lot of dnd players aren't comfortable with having characters weakened in this way. Cosmic horror (or Call of Cthulhu) is not for everyone. That's why the dm can homebrew cures. All dnd adventures are meant to be tailored to the dm and the players. That's what session 0 is for.
You get corruption when you roll a 1. But what about halflings? Should you keep the corruption because you rolled it, even though you might reroll? Or are halflings just naturally resistant to corruption (which would make thematic sense)?