Looking Upon the Face of a Dead God: the aftermath of a 1D10/1D100 SAN test

art from Lovecraft: The Blasphemously Large First Issue by Daniel Govar and Mat Lopes

In Delta Green, if a Great Old One makes a big enough appearance in the game for you to have to make a SAN roll, the game's usually over. But sometimes it's not the end. Maybe a Shan only briefly exposed your mind to Azathoth as a punishment, or like Johansen, you ram Cthulhu in the face with a steamboat, who understandably decides to go back to sleep. You've still lost 1D10, 1D20, or 1D100 SAN, which is an awful lot. Just because Yog-Sothoth didn't let the Old Ones break through and trample all over the earth doesn't mean you survived. There's a good chance you're babbling at 0 SAN or some other number low enough for an exit from field work. In this post, I'm going to crunch the numbers to find the probabilities of the different results of a 1D10/1D100 or 1D20/1D100 SAN test.

Guest Post: The Prosecution Rules

I did some math relating to the prosecution rules (AH page 80), and found that due to a quirk of those rules, a trained lawyer using his 50% Law skill to work the system has next to zero impact on average. More surprisingly, using his main professional skill for its intended purpose actually puts him at a slight disadvantage.

As written, a character's attempt to make the legal system work in his favor uses a Law roll to generate a modifier to a Luck roll. If the Law roll crits, the Luck roll is made at +40%, a success makes it at +20%, a failure at -20%, and a fumble at -40%. On it's face this sounds fair, but for reasons we'll get to later it is actually quite unusual for DG.

The Stats Chamber: A Tool for Handlers

How This Came to Be

Sometimes when you're writing a scenario, you want to know exactly how dangerous an attack is to ensure a certain game experience. Maybe you've killed a bunch of Agents before with situations you thought were relatively safe and want to avoid making the same mistake. Maybe the narrative pacing requires an enemy dangerous enough to command attention but not so dangerous that it wipes the party. In either case, you have some math to do so you can make an informed decision on what damage to use.

The Resistance Table

In Call of Cthulhu, there was a mechanic called the Resistance Roll, to be used when two characteristics were pitted against each other. It could represent shoving someone out of the way, STR vs SIZ, or an Investigator dying from poison, CON vs POT (the potency of the poison). A simple but clunky formula gave you the chance of success given the characteristics, but there was also a table that had the math already done for you for characteristics from 1 to 31 against characteristics also 1 through 31. The seventh edition of CoC did away with this mechanic, as did Delta Green, which replaced it with the opposed roll. So why do we care about this defunct mechanic? Lots of folks like to use CoC content in their DG games (including old DG content published for CoC) and the Resistance Roll is a tricky mechanic to convert. This post seeks to compare it to DG's opposed rolls and offer some conversion advice.

A History of SWORDS (and how to fix them)

Chainmail, OD&D, and Magic Swords

One of the classic tropes of D&D, for good or ill, is the magic sword. A sword that is just magically better at doing its job of hurting and killing people. Maybe it has a few other properties like glowing blue in the presence of orcs or evaluating the "alignment" of the person holding it. But at the most basic level, it's a +1 sword. When you make an attack roll, you add an extra +1 to the D20 on top of whatever you would add from your class or ability scores, and you add an extra +1 to your damage roll. However, in OD&D, the latter was not the case and magic weapons only improved your chance to hit.

Unsurprisingly, this is not incredibly impactful. You're increasing your chance to hit by 5% and your damage by about 20%. However, players mostly care about their hit-chance as that's what they get immediate feedback on. Additionally, the damage boost is not as impressive as it might seem once you realize its goal, reducing the enemy's HP to zero. Against an enemy with 1 hit-die (HP rolled randomly), the chance for a single sword-stroke to slay them only increases by ~10% when you add +1 to your damage roll. This conflicts with the supposed idea of magic swords as presented by both Chainmail and OD&D. Each one was supposed to be a rare thing with its own personality and name. That's a level of importance that doesn't seem fitting of such a slight increase in fighting ability. However, this makes more sense when you realize that OD&D was initially supposed to use Chainmail's combat resolution system.

The Glaakeen, an Old Threat for Delta Green

untitled 'doodle' by Asta Daily

In the Handler's Guide, in Glaaki's part of the Great Old Ones chapter, we learn about the Glaakeen (or Servants of Glaaki as they're called in CoC). Most of them hang around Glaaki and presumably do his bidding, but they also show up in Glaaki cults, most famously under the leadership of the Fate's Belial/Robert Hubert in Holy War in Eyes Only. In fan content, they're well suited for the dual role of 'muscle' and 'ascended elders,' a bit like how Deep Ones act in some Cthulhu cults. We're given 'stats' for them in one of Glaaki's abilities in the Handler's Guide, but it is incomplete if you want to actually use them.

Simplifying B/X's Saving Throw Matrices

I like the old saving throws. To no one's surprise, my favorite incarnation of them lies within the pages of Moldvay's B/X. However, they're not perfect. They rely on a series of tables that aren't the easiest to reference quickly. It's not uncommon for one's eyes to slip and read off the wrong number. This is more of an issue for the Dungeon Master than the player, but it's not the primary problem: the saving throw progressions aren't smooth.

"But Top Hat," I hear you say, "why does that even matter?" I will admit, it's a bit of an obsessive mathematical yearning but it's in contrast to almost all of the rest of the game's mechanics. HP progression is smooth, each level, you get more HP. Spells and spell slots are smooth, barring a few levels where you get multiple at once, you get a new spell slot each level. THAC0...okay THAC0 isn't quite as smooth but it's still smoother than saving throws. Thief skills go up by 1% or 5% each level. A cleric gets incrementally better at turning each level. In contrast to that, saving throws do nothing for three (or five if you're unlucky enough to be a Magic-User) and then improve by several points all at once. And the rate of advancement doesn't even hold constant. It's a mess!

An Analysis of SAN Loss in Delta Green

When Agents (and theoretically NPCs) encounter unnatural beings, they usually have to make a SAN test and risk losing some SAN. Most SAN losses in Delta Green follow a rule of thumb set out in the Agent's Handbook's Sanity chapter.

If the cost of failing a SAN test is 1D6 or less, the cost of success is usually zero. If the cost of failure is 1D8 or 1D10, the cost of success is usually 1. Some unnatural events and encounters are even more catastrophic (AH, 66).

You can map out the progression of SAN loss like so: 0, 0/1, 0/1D4, 0/1D6, 1/1D8, 1/1D10, 1D4/1D12, 1D6/1D20, and 1D10/1D100. We don't find 1D10/1D100 until we open the Handler's guide, and 1D4/1D12 is purely a theoretical SAN loss that fits very nicely between 1/1D10 and 1D6/1D20 but I've never seen it in any published DG material. 

EDIT: as of Fall 2021, we actually now have an official 1D4/1D12 SAN loss in ARCHINT.

Some listed SAN losses deviate from this progression. Most of these anomalies are unnatural, but first I'll cover the mundane anomalies found in the Agent's Handbook.

Rolling up a Wizard for Begone, FOE!

One of my friends, mellonbread, wrote up a dungeoncrawling game. If you follow the blog, you've seen me mention it before. I've been helping him turn it into a complete system by writing up a bestiary. Most of my inspiration was drawn from B/X, though I grabbed some cool monsters from AD&D and other editions and retroclones. A lot of these monsters are people, or rather, humans with class levels. 

This poses a particular problem for magic-users, as their spell selections are to be determined randomly. Lots of other games make this pretty easy. A wizard has a number of spells of a certain level that they can cast per day. You consult the table and roll up the appropriate amount of spells. WotC made it even simpler in 5e by giving archmages and priests set spell lists in their statblocks.

However, that doesn't work for Begone. There aren't any spell slots per day of a certain level. It's more vancian than any TSR or WotC edition of D&D ever was. The more powerful you are, the more powerful spells you can hold in your head. This could either by one big spell, a lot of little spells, or a mix of something in between. So how do we decide what "loadout" a wandering wizard has?

An Analysis of the "Defensive Properties" of Creatures in Delta Green

WARNING: This post sort of contains spoilers for some creatures and mechanics in the Handler's guide. If you wish to remain unspoilt as an Agent, read no further.

Delta Green is filled with various critters, some unnatural, and some completely mundane. However, all of them usually have what the Handler's Guide calls a "Defensive Property." This blogpost exists to expand upon the "Creating Your Own Unnatural Threats" chapter. I think it's a good resource, but it glosses over the finer details of DPs, plus I have my own bones to pick with a few of them.

Stealth and Surprise in Begone, FOE!

 So one of my internet friends wrote up a system because he was tired of adding house rules to B/X but still wanted something that could run "old school content." I've played in it a whole bunch and I think it's pretty neat. In fact, right now, I'm working on some stuff I intend to run in the system.

This is the Surprise Table, as of revision eight, at least.

Roll	Result
1-4	Monsters alerted to players’ presence, players unaware
5-10	Monsters and players fail to detect each other and “surprise” each other
11-16	Monsters and players both detect each other at the same time
17-20	Players alerted to monsters’ presence, monsters unaware

Analyzing Delta Green's Monsters via Average Damage Output (and other things)

This post will be a little outside my usual repertoire. For those of you who don’t know, my other RPG of choice besides a mishmash of OSR titles (and whatever home-brew I happen to be toting around at the time) is Delta Green. The Handler’s Guide has a monster manual of sorts and in the interest of laying bare the mechanical underpinnings of games, I now tackle the average damage outputs.

But before I get to the actual “math,” I need to decide how I’m going to deal with the Lethality mechanic. It’s a common feature among unnatural beasties but the trick is that it doesn’t deal HP damage like everything else. It just reduces your HP to zero, ignoring armor, basically killing you. Even the one spell in the game that might complicate this with magical armor doesn’t. If you have a single point of Armor from Exaltation of the Flesh, you’re immune to successful Lethality rolls, taking normal HP damage. However, there is a handy part of the rule: successful Lethality rolls ignore Armor. So rather than treating it as infinite damage, I can instead treat it as 18 damage, enough to kill even the toughest Agent from full health. A quick glance at the back of the Handler’s Guide also shows that this still roughly works for all mundane creatures that still interact with this part of the Lethality mechanic. The others that have significantly more than 18 HP take flat damage to the Lethality rating, thus sidestepping the problem. 

The fact that successful Lethality rolls ignore body armor can be represented by thinking that these average damage values have a Lethality% chance to ignore body armor. Or on the scale of averages, only (100-Lethality)% of your body armor actually applies.

However, Lethality doesn’t always ignore Armor. If you have Cover, which also gives you Armor, the Lethality roll automatically fails and deals normal HP damage. So wherever it’s appropriate, I’ll be splitting the average damage of Lethality attacks into “against Cover” and “not against Cover.” Other relevant considerations like Armor Piercing and whether or not the attack should be able to used to Fight Back will also be notated. I’ll also be including Lethality ratings to put perspective on things.

Agents read no further I guess?

Unifying B/X's XP Tables

NOTE: This post is filled with a lot of digital ink spilled over the design of early D&D. If you want the unified XP tables and don't care about any of the theory, just skip the opening paragraphs.

Coming from the perspective of modern D&D, B/X has some immediately noticeable divergences, most notably: the variable XP tables, race-as-class, and those wacky five saving throw categories. There's more differences, but you have to dig a bit deeper to find them.

As I understand the history of D&D, variable XP tables were ditched during the transition from AD&D to third edition in order to facilitate multiclassing. There were rules for it before, but like everything in AD&D it's a giant complicated mess that even my autistic brain doesn't want anything to do with.

While not exactly the most precise, there are design principles in early D&D. These principles are the reason we have the variable XP requirements in the first place. They're there for "balance," as weird as that may sound. A lot of people associate that term with modern D&D with its preoccupation (and oftentimes failure) with making sure no one class or ability overpowers another and that encounters are scaled to match an adventuring party's capability. This too exists in early D&D.

Dwarves are like Fighters but with some added benefits (better saving throws and chances to detect dungeon tricks) so it costs more XP to level up. Halflings don't have access to the wide variety of weapons that Fighters do, nor do they have the tough eight-sided hit die, but they have a variety of sneaky tricks at their disposal. So overall, it's a net zero effect and they level up at the same rate as Fighters. An Elf is basically a Fighter and a Magic-User (a holdover from OD&D and a better implementation in my opinion) so they cost an insane amount of XP to level up, 4,000 experience points to reach level 2. The Thief has a paltry d4 hit die and their only draw is their "Thief Skills." So to compensate, they level up faster than everyone else. And the Cleric levels up faster than the Fighter for some reason.

I don't mind the variable XP requirements and the last time I ran an osr (a hack of LotFP), the Thief player was delighted to hear that they'd be leveling up much faster than everyone else in the party. However, I like math and the balancing that results from variable XP is...kind of artificial so I'm happy to try my hand at unifying the XP tables while not rewriting the system from scratch.

"But Top Hat," I hear you say, "didn't some osr bloggerman write up a unified theory of XP progressions for B/X? Why not use that instead?" To that, I have two responses.

1. As much as I love it, B/X isn't a perfectly tuned machine. You can fudge the numbers. 
2. I might be using that post to "double check" my math in a followup post.

Based on some back-of-the-envelope math I did in a TextEdit document (don't ask), Clerics and Thieves are roughly half a level ahead of Fighters, Magic-Users are about half a level behind, Dwarves are slightly less than a third of a level behind, and Elves are basically a full level behind. And as an additional note, I didn't come up with all of this myself. I was helped in part by some kind grognards on the internet, you know who you are.

THE CLERIC

The way this holy warrior class advances faster than the normal warrior never made sense to me. You can bump them up to a Fighter XP progression and no one will notice, it's not until 13th level that they're a full level ahead of their secular counterparts. If you want to make yourself feel better, get rid of their weapon restrictions. Tie it to their specific religion and let the cleric atone if they break the taboo.

THE DWARF

Bump them down to the Cleric's attack progression. Boom. Done.

THE ELF

This one is trickier. You can bump them down to Cleric attacks, but that still leaves their spellcasting abilities to deal with. However, because the fey spellswords are, on average, a level behind, you can just delay their spell progressions by one level. After all, we plan on shifting Magic-Users down to a Fighter's XP progression next. They'll start off knowing zero spells (maybe a few cantrips if you give those to Magic-Users anyway). They can earn their keep at level 1 with their reduced surprise chances, secret door finding abilities, immunity to ghoul paralysis, "darkvision," and ability to use scrolls and wands. If that seems too overpowered, you can just chop off whichever one of their abilities you're least fond of (I'd go after darkvision).

THE MAGIC-USER

In my opinion, the spellcasting ability afforded to Magic-Users isn't too powerful. Their spells and spell list is very limited and it's not until 11th level that they're lagging a full level behind Fighters. However, we can't just handwave it, after all, Magic-Users do get pretty powerful at later levels. This is in part due to how they start gaining multiple new spell slots per level starting at 7th level. So an easy fix is to not let this happen and leave all the lower level spell slots at a maximum of 2. 

Disclaimer: not mine, entirely too neat and professional looking

Or you can give them a spell progression as shown above. This gives lower level Magic-Users a bit of a boost but heavily clamps down on higher level casting power.

THE THIEF

These sneaky bastards are also tricky. You can bump up their hit die to a d6 and maybe boost the chances of their Thief Skills by a little. You could also take a cue from AD&D 2e and allow the player to choose where they allocate their skills or steal the Specialist from LotFP. The last suggestion is so clever I wish I'd thought of it myself but alas I did not. Thieves now attack and save as one level higher. Basically, your THAC0 improves from 19 to 17 at level 4 rather than level 5 and so on. It's a small but meaningful boost that reflects their speedy advancement under the original rules.