Can Superheroes See Invisible?

Consider the O/AD&D Superhero -- a.k.a, the 8th-level Fighter. If you blink you'll miss it, but in multiple places in early texts it says that fighters of that level can automatically see invisible enemies. (!)

Here's the Fantasy Reference Table from the Chainmail game (included by reference in multiple parts of Original D&D), with key parts highlighted:

Now, you might possibly think that's a typo or something, except that it gets restated in Original D&D, Vol-2 (the Monsters & Treasures booklet), specifically in the entry for Pixies:

PIXIES: Air sprites as described in CHAINMAIL, Pixies can be made visible, or make themselves visible, but they are naturally invisible to human eyes. Therefore, they are able to attack while remaining generally invisible. They can be seen clearly only when a spell to make them visible is employed, although certain monsters such as Dragons and high-level fighters will be aware of their presence.

A few years later, the Advanced D&D game generalized this ability, such that any high-level creature had some chance of detecting invisible. However, the chances of success are much reduced. For example, the 8th-level Superhero fighter now needs a very high Intelligence score, specifically 15 or higher, to have even a 5% chance of detecting invisible in a given round. Here's this table from the 1E DMG p. 60:

This seems like an odd rule: counterintuitive, easy to forget, unlikely to come into play in most games. And under the interpretation seemingly shared by the earliest designers -- that OD&D and AD&D were a single continuous game undergoing some evolution -- this seems like a case where Gygax was quickly becoming disenchanted with the rule; radically dialing down the likelihood for standard high-level fighters, for example. I take this as evidence that the clear intent was to largely take the ability away from standard Superheroes after some amount of playtest experience in D&D. (And of course this general rule was sufficiently fragile that it disappeared in later editions.)

Separately: As usual for O/AD&D, if you disentangle the numbers in that 1E table, you'll find that the progression on each axis is mostly linear. You could get a good approximation of that rule by doing the following:

Roll 1d20 + Level + Intelligence and score 40 or more.

Or in Target 20 terms: roll d20 + Level + Intelligence - 20 and get a total of at least 20.

But would you want to use such a rule?

Consider Chaos

I had an experience the other day where, trying to resolve an issue, office A told me it's the job of office B, office B said to talk to office C, and C said I had to talk to A. This is not uncommon. Things are pretty chaotic.

The next time you lay out a dungeon or lair of a bunch of chaotic monsters, consider the chaotic people and institutions in your own life, and see if injecting some of those details doesn't heighten how bewildering they are (or at least give some catharsis to you). I'll say as someone just slightly on the spectrum, it's somewhere between challenging and painful to imagine a world that works like this -- but it is the world I live in.

Some seeds for thought:

• Cave A, B, and C have the same monster type, but they don't coordinate in any way.
• Different caves have different "bosses" who are in direct competition with each other.
• There's a "king" monster but (like the book says), their immediate command is only the people in direct line of sight. They can give dictates to the larger complex, but it's always a per-area reaction roll to see if they are obeyed or not.
• Cave A and B are the same clan, but due to a feud they haven't communicated in several years.
• Cave A may have information the PCs can cajole, bribe, or force out of them: details on people, places, things, passwords, maps, etc. But they're simply wrong, and the monsters in Cave B say they've never heard of any of them. Maps are incorrect. Passwords are out of date.
• Cave A has certain protocols that are maintained for weeks or months: a patrol schedule, name of a boss, guardian monster pass, puzzle-lock pattern, etc. Then one day it doesn't work like that and everyone denies any knowledge that it was ever different.
• The tribe is known for using a particular weapon (say: long spears). Then one day the king announces that these are now anathema (due to a scroll, religious revelation, wormtongue consultant, etc.), and every such item in the tribe is burned in a great bonfire. The tribe starts manufacturing swords and shields; this works poorly, so, some months later, they switch back.
• Monsters are not proficient with the new weapons they've recently been given. Or, they've had them for some time but never received any training.
• The king has a cool magic item but can't use it. The shaman is currently on the 5th cycle of divining a series of control words for it, none of which have worked when the king goes to use the item in a crisis.
• Any idiom you can possibly think of gets misconstrued. "We need to see the boss! - We don't allow portraits in here." "I'm all ears - That's horrible, I'm glad you masked yourself with an illusion." "That'll be a piece of cake - I had cake once, I challenge you to the death for it."
• General willingness to give BS responses (in the Frankfurtian sense) randomly on any issue, large or small.
• Claims to great monsters, defenses, or treasures that simply don't exist.
• Boss monsters who run away immediately and let their goons die to cover their tracks.
• Numbers in the lair may go up or down randomly between sessions as other monsters are recruited/dismissed for various reasons.
• Various cargo-cult rituals occur; claims to magic power, alien gates, etc. The majority do nothing. Can the PCs depend on them continuing to do nothing as they try different things in the future?
• Scrolls & spellbooks of twisted, semi-cursed versions of standard spells.
• Bosses reactions: Always screaming random directions. Often self-contradictory.
• Tribe has a series of religious dictates which are all vocally worshiped and ignored in practice.
• Door with a puzzle lock unknown by anyone in the tribe. Maybe there is no solution.
• One low-level member of tribe actually has solution or passkey for a certain puzzle, trap, or monster, but no one believes them, because they're politically disempowered. Who is it?
• Key tribe members are mostly drunk or drugged on a regular basis.
  
• Going darker: The tribe randomly accuses some of its members of non-existent heresy and imprisons or tortures them, to no benefit.
• The tribe ejects members randomly for various infractions. And/or: If members seek to leave, they are captured and imprisoned instead.
• Townsfolk are kidnapped: And some random proportion are afflicted by the chaos of the place with Stockholm syndrome and surprisingly fight for their captors.
• The tribe is spending a great deal of resources to defend themselves from a nonexistent threat (fictional monster, enemy tribe, made-up curse, cult, etc.) Meanwhile there's an actual disease, poison gas, parasite infestation, or geologic catastrophe that's degrading the tribe and being scrupulously ignored.
• The tribe practices culling of a certain part of its population (based on age, gender, physique, etc.) They then have a problem of being over-biased in one direction, so they flip to culling the opposite part of the tribe.

At a somewhat higher level, consider if reality itself isn't morphing all the time, faerie-style:

• Room furnishings and decor are changed frequently to their exact opposites semi-randomly.
• NPCs show up in sequential encounters with somewhat changed hair, body, facial features (scar switches side), vocal tics, etc.; and show no awareness they were ever different.
• Magic tricks, traps, puzzles, riddles, etc., get morphed on different dungeon delves.
• Time slows down or speeds up in different parts of the dungeon, randomly in different sessions.
• The spatial map layout of the dungeon, and possibly the surrounding wilderness, likewise shift between different sessions. Connections appear and disappear. Rooms gets closer or further apart. (Note: I've wanted to implement this for some time, but creating a nice keyed map takes so much time, it's difficult to commit to re-generating it on a regular basis. Some software tooling that "rubber-sheets" the map would be really great.)

I'm sure you can think of more examples. Just reflect on the institutions closest to you and riff on out-of-control processes you've seen yourself. Write a dungeon background key as normal; then go through every sentence and roll for whether that really is how things work - in contrast to how the inhabitants think/claim it works. Go read Stack Exchange: Workplace and fold in various absurdities.

In conclusion: The classic trope of a dungeon with monsters in nearby rooms or caves who are totally disconnected, without any communication or coordination, is actually not that unrealistic. It happens around us in the standard workplace all the time. Let your players experience the force of true chaos!

The Gygaxian Hallway

It's something of a common gag that in the earliest D&D dungeons, all of the hallways were composed of 10-foot cubes -- but it's not true (notwithstanding the customary backstory to the gelatinous cube).

If you look in the right places, Gygax was surprisingly consistent about the shape of his hallways -- and they look like the image at the top of this post here. This is from the original Temple of Elemental Evil (1985), p. 40, in the introductory material to the temple proper. (Note like most art pieces in the extended module, it's signed "Jack[ie] Fred", which is a pseudonym shared by a number of artists when they were unhappy about the time constraints to do their work; but this definitely looks like a Jeff Easley illustration to me.)

In the text, the very first thing detailed in Part 3: Dungeons of Elemental Evil (p. 43) is is the information on "Standard Corridors", which describes the same architecture. This paragraph reads as follows:

Unless noted otherwise, corridors are of dressed stone blocks or worked from the natural limestone (or granite, in the lower depths). Walls and floors are smooth and polished wherever possible. The 10' wide corridors have gothic arches, peaking at about 17' height. The 20' and 30' passages and spaces have roman arches, about 30' tall. Unless otherwise described, doors are of oak, homwood, or bronzewood. Each is about three inches thick, bound with bronze, and set with a large ring on each side. Cressets and sconces are along the walls, and unlit torches rest in most of the latter. In 10' wide corridors, sconces are at 10' intervals. Cressets in wider passages are at 30' intervals. Both are staggered left, right, left, right (etc.), and unlit unless specified.

Almost a decade earlier, Gygax specified almost exactly the same thing in the 1E AD&D PHB's description of the wall of stone spell (p. 82):

This spell creates a wall of granite rock which merges into adjoining rock surfaces if the area is sufficient to allow it. It is typically employed to close passages, portals, and breaches against opponents. The wall of stone is 1/4' thick and 20' square in area per level of experience of the magic-user casting the spell. Thus, a 12th level magic-user creates a wall of stone 3' thick and 240 square feet in surface area (a 12' wide and 20' high wall, for example, to completely close a 10' × 16' passage).

Moreover, one page before that, the passwall spell is described as creating a passage of exactly half that standard size in each dimension:

A passwall enables the spell caster to open a passage through wooden, plaster, or stone walls; thus he or she and any associates can simply walk through. The spell causes a 5' wide by 8' high by 10' deep opening. Note several of these spells will form a continuing passage so that very thick walls can be pierced The material component of this spell is a pinch of sesame seeds.

I suppose we might say that latter spell is making a door-sized opening (if we ignore times the DMG asserts that standard dungeon interior doors are a tremendous 8' wide: see p. 60, p. 97, and my commentary here).

Anyway, this consistency in scaling seems unlikely to be a coincidence. I'd say it's an easy call that the dungeons underneath Castle Greyhawk had this same architecture, for example. Keep in mind the extra space overhead for that Gothic arch when it's important. Can you find any other references to dungeon hallways being this specific shape?

Monsters Through the Ages -- Carrion Crawler

Last week on Wandering DMs we had a smashing chat with one of our favorite repeat guests, Matt Finch of Mythmere Games. As I write this, his Kickstarter for the new Swords & Wizards Complete Revised edition is entering its last few days -- you should check it out if you can. 

Matt is both epically knowledgeable about old-school D&D, and also impressively generous with his time and wisdom. After the live show he hung out for another hour to chat with he patrons on our Discord server (accessible at any tier on our Patreon). As part of that discussion, we got on the subject of Carrion Crawlers. Almost everyone involved had a different take on some part of how they should work -- and as we dug out our various books, it turns out that every one of our competing interpretations had some support from one text or another, which was entirely fascinating.

The Carrion Crawler is rather infamous for being probably the most brokenly imbalanced creature in early D&D. Positioned as a 2nd level monster on its birth in OD&D (Supplement I), it was re-evaluated as 6th level in the AD&D DMG, and got a special badge in its Monster Manual text: "... these monsters are greatly feared". Don Turnbull's MonsterMark System from the White Dwarf has an especially problematic time handling it. Frank Mentzer put forward using one as the single biggest mistake of his DM'ing career. And on and on. But what makes it the flagship for busting up a DM's best-laid plans?

OD&D Greyhawk (1976)

CARRION CRAWLERS: These scavangers will usually attack in order to insure that there will continue to be a supply of corpses to scavenge. They are worm-shaped, about 9’ in length, 3’ high at their head end, and move quickly on multiple legs. Their mouths are surrounded by eight tentacles of about 2’ length, and their touch causes paralization (save vs. or paralized). The Carrion Crawler is able to climb/move along walls or ceilings as readily as floors, thus allowing it to compete with Ochre Jellies, Black (or Gray) Puddings, and the like.

The "Attacks and Damage by Monster Type" table in this book (p. 16-19) confirms that a carrion crawler gets "8 tentacles" for its number of attacks, which is a very large number (rivaled only by octopi, squids, and hydra). The damage entry just says, "special", and the text here notes the paralyzing attack, which is really crippling (e.g., its one of the reasons ghouls punch so far above their weight class by hit dice). 

Note that no actual damage value is given -- I think this and the rust monster are the only two creatures to this point that lack a damage value or some other clear way of killing a PC (i.e., by poison or other death effect). This makes it a major trap and counterexample for any system that tries to measure monster threats by some kind of a-la-carte points system.

In our discussion last week, several opinions were put forward about what happens, as is quite likely, after a carrion crawler scores a TPP (total party paralysis). Does it just wander off, looking for actual dead mat (carrion), no-harm-no-foul? Does the DM start making wandering monster checks, who might actually kill the PCs and thus give the crawler something to scavenge (note that no duration was given to any paralysis abilities to this point). Does it presumably auto-consume the hapless PCs? Yes to all of these, depending what edition you play with.

AD&D Monster Manual (1977)

...

NO. OF ATTACKS: 8
DAMAGE/ATTACK: Paralysis
SPECIAL ATTACKS: As above

...

Carrion crawlers strongly resemble a cross between a giant green cutworm and a huge cephalopod. They are usually found only in subterranean areas. The carrion crawler is, as its name implies, a scavenger, but this does not preclude aggressive attacks upon living creatures, for that insures a constant supply of corpses upon which to feed or for deposit of eggs. The head of the monster is well protected, but its body is only armor class 7. A carrion crawler moves quite rapidly on its multiple legs despite its bulk, and a wall or ceiling is as easily traveled as a floor, for each of the beast's feet are equipped with sharp claws which hold it fast. The head is equipped with 8 tentacles which flail at prey; each 2' long tentacle exudes a gummy secretion which when fresh, will paralyze opponents (save versus paralyzation or it takes effect). As there are SO many tentacles with which to hit, and thus multiple chances of being paralyzed, these monsters are greatly feared.

A year later we have the 1E AD&D Monster Manual, which is almost entirely backwards-compatible with OD&D, and mostly just compiles all various stats for each monster (formerly spread around in separate pages of each book) in one place. It still gives no positive damage other than the paralysis effect, and no duration for that ability, either.

The text says that it's willing to attack living things, "for that insures a constant supply of corpses upon which to feed or for deposit of eggs". Without any specific mechanics, this could open up DM to interpret it in several ways. Maybe paralysis leads to death; maybe it waits for wandering monsters; maybe it injects eggs into PCs who get consumed by them immediately or later. The mind boggles at the hideous possibilities. 

D&D Basic Rules (Holmes, 1978)

This scavenger is worm shaped, 9' long, 3 feet high at the head and moves quickly on multiple legs. It can move equally well on the wall or ceiling as on the level. The mouth parts are surrounded by eight tentacles, two feet long, which produce paralysis on touch (i.e. when a hit is made). 

Holmes Basic is usually a faithful editorial presentation of the same rules as seen in OD&D. I briefly point out this book because it more explicitly gives a stat block for the carrion crawler that says, "Damage: 0". Zenopus Archives has a great series poring over the original Holmes manuscript for this book, which we know Gygax did an editorial pass on before publication. (And he makes the point that possibly one could argue in OD&D that by default every crawler tentacle gets a stock d6 damage on every hit, but that's taken off the table with this clarification.)

D&D Basic Rules (Moldvay, 1981)

This scavenger is worm-shaped, 9' long and 3' high with many legs. It can move equally well on a floor, wall, or ceiling like a spider. Its mouth is surrounded by 8 tentacles, each 2' long, which can paralyze on a successful hit unless a saving throw vs. Paralysis is made. Once paralyzed, a victim will be eaten (unless the carrion crawler is being attacked). The paralysis can be removed by a cure light wounds spell, but any spell so used will have no other effect. Without a spell, the paralysis will wear off in 2-8 turns.

As usual, Tom Moldvay makes the helpful decision to specify a duration for the paralysis for the first time. His stat block is back to saying, "Damage: Paralysis" (as opposed to 0 in Holmes). But most keenly he states that crawlers simply eat their paralyzed victims by fiat. (!) So DMs used to running the B/X or related systems likely have the intuition that crawlers just swallow their prey whole like a snake. No save for you.  

This same ruling is carried forward later into the Mentzer BECMI set. The Alston Rules Cyclopedia is largely the same with tiny adjustments: the stat block there says, "Damage: Paralysis or 1 point", and the text sets a timer on fast one eats paralyzed bodies: they "will eat paralyzed victims in three turns".

AD&D Monster Cards (1982)

Carrion crawlers attack with 8 tentacles that secrete a gummy fluid that will paralyze any opponents hit for 2d6 turns unless they save vs. Paralyzation. Carrion crawlers wll continue to attack as long as any opponents are unparalyzed. They will kill paralyzed creatures with their bite (DM 1-2), in order to have a constant supply of bodies to eat and to lay eggs in.

The AD&D Monster Cards are kind of a fascinating a beautiful set of products (the art at the top of this post is the front of the Carrion Crawler card). There are times I'm tempted to run a classic game by always showing players these cards, with name and info hidden on the back -- except there are too many gaps of key monsters that were never included (please, someone make a fill-in product here, take my money so I don't have to do it).

While the stat blocks are mostly identical to what's in the Monster Manual, these cards make some surprising, fundamental tweaks to certain monster rules. For example, you can see here that it specifies values for carrion crawler paralysis time (2d6 turns) and its capacity post-paralysis (a bite attack for a 1-2 damage). Other examples include specifying the duration for Ghoul paralysis for the first time in the game. So now the issue clarified for the AD&D line: a paralyzed party will clearly get TPK'd by the crawler. 

This duration and damage was copied forward verbatim into 2E AD&D, for example. In 3E the duration was given as 2d6 minutes, and the post-paralysis bite damage was raised to 1d4+1.

Big thanks to our patron Adam for pointing out this detail to us.

Conclusions

At the outset, carrion crawlers has a fairly open-field ability profile that DMs could potentially fill in many different ways. But over time each of the bifurcating Basic and Advanced D&D lines of the 1980s-1990s came around to specifying a relatively limited paralysis duration, and a direct way for crawlers to finish off prey that they'd paralyzed -- including some small-damage bite attack in their final forms. 

Even with that specific damage figure, their main disabling threat is of course the paralysis ability, so systems that try to mechanically crunch damage numbers will still trip up over evaluating these monsters. In the OED Monster Metrics simulator, a carrion crawler with its full 8 attacks gets assessed at EHD (equivalent hit dice) 12, while a reduced one with 4 attacks is still EHD 9. (Note that latter form is what I customarily run with, coincidentally similar to what Mentzer rationalizes in his games.)

How do you like your carrion crawlers? Are you happy with the post-Moldvay consensus that crawlers definitely terminate their paralyzed prey, or would you prefer different possibilities?

Random Walks in the Dungeons of the Slave Lords

I recently had an opportunity to run AD&D module A4, In the Dungeons of the Slave Lords, for the first time. This is of course the culminating adventure in the classic A-series Slavers tournament, famous for stripping the PCs of literally every resource and forcing them to outhink their way through a pitch-black labyrinth after being abandoned/ sacrificed to its horrors. We chatted about it a bit on Wandering DMs the other week. 

Once again, the playthrough made me realize several things about the adventure that I hadn't noticed, even having read through it multiple times since its release in 1981. (As usual, one of the pieces of dogma for this blog is: The acid test is gameplay.) One that came up in my discussion with WDM Paul is that, while the dungeon has 3 different possible exits, all the times we've run it the players have made it out through one exit in particular.

To investigate this, I took some graph-theory code I'd developed for one of my college courses, modeled the A4 dungeon as an abstract graph, and then simulated several thousand random walks starting from the entry area #1 to see the frequency that those walks run into the various exits. For this purpose, I annotated the dungeon map with extra areas 22-27 to mark otherwise unlabelled tunnel intersections (if you have your own map copy you can deduce where I put those labels, I'm sure). Then I cut out all of the mid-tunnel points that don't have any branches, places where the PCs are highly unlikely to turn back, counter to how a random walk will work (and this also simplifies the visual appearance of the graph, below). Here's the result, via the gvedit visualization tool:

 

Some observations: There are several interconnecting circuits in the section of areas #1-12 (top half of this graph), which allow numerous ways to navigate between those areas. But there's only one exit in that section, at area #10. 

In contrast to that, there's one critical bottleneck-tunnel from area #12 to #15; that's the only way to access the other branch composed of areas #15-21 (bottom half of the graph here). Despite the difficulty in getting there, that branch includes 2 of the 3 dungeon exits (at areas #19 and #21), as well as the notable Myconid colony (featured on the cover of the module, and the only place in the entire A series where negotiation can be profitable). If players never find their way to that particular tunnel out of area #12, then they'll never see any of that latter content.

So here's the results of my series of random walks -- note this is purely random at each location, including equal chances to turn around and backtrack from any location. After 10K simulations, the number of times each exit was reached are as follows:

AD&D Module A4 Random Walks 

Exit	Reached	Percent
10	5,360	53.60%
19	1,904	19.04%
21	2,736	27.36%

So broadly speaking, this model suggests that about half the time, players will exit from the top half of the graph, which means the exit at area #10. And the other half of the time, players will exit from the bottom half of the graph, with exits split between areas #19 and #21. Basically that toggle is a coin-flip over whether they take the tunnel from #12 to #15 or not. And consider that in this scenario, the players aren't allowed to map or properly orient themselves ("all directions should be given to them in terms of right and left", p. 3), so it's at least as likely that they'll circle back on their own path several times as they are to stumble onto the key connection. Indeed, it's the exit at #10 from which Paul & I have seen all of our playgroups escape (a small sample size, to be sure).

Regarding the difference between the two exits in the far part of our graph: our model makes it look significantly more likely that #21 is found than #19. On the other hand, it's the latter area that the Myconids are able to direct the players towards, which might shift some weight from #21 to #19; but on the other-other hand, anecdotal evidence suggests the Myconids are so frightening that it's rare for negotiations to be pursued with them. Since all of these factors are isolated in our lower branch, I don't think any such re-evaluation would affect the chance that area #10 is discovered first.

Here's he upshot: If you're preparing to run module A4, then you should prioritize being able to handle the #10 exit above the others, and more generally the whole branch that it's on, because it looks like a bit more than half the time that's how the action will play out. Secondarily you can prepare for running the more distant branch (with the complex Myconid area), in particular the area #21 exit, and not spend too much time thinking about #19, which seems to be a fairly unlikely exit point.

If you've played or run module A4, which exits did you personally see get used in play?

The Concentration Game

The issue of "concentration" for spellcasting has come up a number of times in my OD&D games lately. For those somewhat more familiar with the current-edition of D&D, two reactions are halfway common: (a) surprise that a "concentration" mechanic existed in OD&D, and/or (b) surprise that it's so infrequently required for spells in OD&D.

At any rate: Yes, Virginia, concentration was a requirement for certain spells in the very first publication of D&D (1974). Just to reflect on it a bit more, here are all the spells which mention such a requirement:

Original D&D

• Phantasmal Forces: "As long as the caster concentrates on the spell, the illusion will continue unless touched by some living creature, so there is no limit on duration, per se". This is the first appearance; kind of interesting it's used as means to avoid giving the spell a defined duration.
  
  
• Wall of Fire: "The spell will create a wall of fire which lasts until the Magic-User no longer concentrates to maintain it." This is one of my least favorite uses (in that it locks the caster down to nothing but maintaining the wall while it's in use -- can't even flee while the wall serves as an obstacle). Requiring concentration while the caster directs some dynamic activity makes sense; just maintaining a static effect not so much.
  
  
• Conjure Elemental: "The Elemental will remain until dispelled, but the Magic-User must concentrate on control or the elemental will turn upon its conjurer and attack him (see CHAINMAIL)." This is likely the most famous, idiomatic usage: concentrate on your summoned elemental or it irremediably go berserk and tries to kill you instead (which is a major downside to this spell!)

And that's it: just those 3 in the little brown books (Volume 1, Men & Magic).

A few other references can be found in Sup-III, Eldritch Wizardry, for the psionic domination ability; and in Sup-IV, Gods Demigods and Heroes, in that the Hyborean magical mirror of Lazbekri requires it (so as to function as a gem of seeing; maybe just flavor text), and that the Indian deity Rudra can cast illusions without such a requirement (as is normally the case for phantasmal forces, above).

So that's a very slight number of uses of the mechanic -- and as usual for the rules in those days, didn't really scope out exactly what the parameters of such a concentration requirement were.

The AD&D rules somewhat expand on those points, including requirements for -- gnome and halfling detection abilities, paladin detection of evil, spiritual hammer, locate animals, locate plants, wall of fire, conjure elementals, clairaudience, phantasmal forces, telekinesis, emotion, a few closely related spells, and numerous psionic abilities (in the optional Appendix I). 

One interesting point is that the 1E phantasmal force specifies that concentration ends with any movement (in addition to taking an attack, etc.), whereas the new improved phantasmal force permits half-speed movement. I find that latter rule pretty reasonable, and use it as a base assumption in my games.

Furthermore, in my Book of Spells (see sidebar) I have a tendency to include it any spells that have an ongoing detection or direction component, including (in addition to the classic ones above) -- read minds (ESP), legend lore, and move earth.

Of course, 5E D&D expanded the concentration mechanic to be a core limiting factoring in a lot more spells -- maybe something like half of all the spells in the game? When playing a caster in 5E, I routinely get tripped up by not foreseeing how many different spells have the concentration requirement, and wind up boxing myself out from good combinations and/or embarrassingly wasting a number of castings.

What's your master theory for what spells should require concentration?

Papier Und Spiele: Book of War vs. Chainmail

Blogger ahabicher at Papier Und Spiele occasionally takes a really close look at my Book of War rules for classic D&D wargaming, and I think it's really helpful to get the perspective of someone who cares so much about D&D mass combat who isn't me. This week he's done a test of a battle between two tribes of warring goblins -- done twice, once in Chainmail, and once in Book of War, to see how they compare. I kind of love this to death. You should read the action. 

In the interest of full disclosure, I will collegially point out a few things in the report that I would personally interpret or run differently:

1. Overall Book of War is trying to simulate classic Dungeons & Dragons combat (with its "Alternative Combat System" as of 1974 with d20 attack matrices), moreso than the original Chainmail book with its custom troop-type tables. That said, I'm constantly referring back to Chainmail myself for lots of stuff like the man-to-man combat sequence, modifiers, creature special abilities, movement and missile ranges, catapult/boulder/fireball targeting mechanics, etc., which are included by reference in Original D&D.
   
   
2. I don't roll initiative every turn, just once at the start of the battle, then alternate sides sequentially. This follows what's in Gygax's later Swords & Spells, but it's opening my eyes for the first time that Chainmail and also Battlesystem determine initiative every round. I can see now in my text I left that a bit vague.
   
   
3. Revisions we've made since the 1st Edition publication adjusted the successful 2d6 morale target from 10 down to 9. This was specifically to synchronize with the OD&D reaction table, which has success at a value of 9 and up (and is referenced as one of the two or three possible ways to adjudicate morale in OD&D: see Vol-1, p. 13). But that wouldn't make any difference in the current play-through, anyway.
   
   
4. There's common debate about whether in Chainmail a player should be throwing 1 attack per figure, or per man (i.e., 20 dice per figure). I do think comes down to sloppy-casual writing in the original Chainmail text, in that Gygax would swap around "man" and "figure" for the same thing interchangeably, even at mass scale. When asked in 2005 on the issue, Gary responded, "Read 'man' as 'figure' and you have it. One die is just that...". You can see the full exchange here. So there's at least an interpretation that allows for much fewer dice when running Chainmail.

That said, I can acclaim enough how incredibly valuable this battle report is! Without giving away exactly how this fight goes, I can't help but highlight ahabiche's ultimate takeaway:

Book of War is faster and easier. It is the better choice to determine the outcome of a battle within the context of a roleplaying game, when we may want to determine the fate of specific individuals by the RPG rules in single combat, and our goal with the mass battle is to find out how it goes.

If you want to see more about the current state of the Book of War ruleset, check out the sidebar, and/or our continuing biweekly series of live playtests on Youtube. Fight on!