Monday, March 11, 2019

Magic Distribution in OD&D Dungeons

An observation: Boy, magic is really rare if using the dungeon treasure table in OD&D Vol-3 ("The Underworld & Wilderness Adventures", i.e., the DM's book). Prior to this table you get the dictate, "It is a good idea to thoughtfully place several of the most important treasures... Naturally, the more important treasures will consist of various magical items and large amounts of wealth in the form of gems and jewelry." Then for the rest of the dungeon, rules that 2 in 6 of rooms have monsters; with treasure present 3-in-6 with monsters and 1-in-6 without. Then this table is given for such treasure:


Now, I've sort of made my peace with this table for gems & jewelry; while rare (esp. at the lower-numbered levels), when present they come in batches and generally large values, so they sort of give some reasonably high value. (A bit like hockey or soccer: scoring is rare but each goal makes a big difference!) However, magic is very rare throughout dungeon levels 1-3, apparently only shows up one item at a time, and has the added limitation that when you turn to the magic tables, 25% of the time it turns into a treasure map, and not actually any magic.

Let's compute. Say on a standard piece of graph paper you get around 40 rooms per levels (that's what I tend to get), and randomly stock the whole dungeon with this method. Then on the first 3 levels combined you'd expect (adding terms for both with-and-without monster cases): 3 levels × 40 rooms × (2/6 with monsters × 3/6 treasure + 4/6 without monsters × 1/6 treasure) × 5% = 120 × (1/6 + 1/9) × 5% = 120 × 0.277 × 0.05 = 1.66 positive results for magic items. Adjusting for the chance of maps, we get 1.66 × 0.75 = 1.25 actual magic items. So on average we may likely get just one single potion on all of levels 1-3 of the dungeon, and no other magic whatsoever. That could make it a bit hard to fight 4th-level monsters like lycanthropes, gargoyles, or wraiths, that start showing up on the [checks notes]... um, 1st level of the dungeon.

Anyway, here's a complete table of expected number of magic items (discounted for chance of maps) per dungeon level under these assumptions:


As we've seen, on levels 1-3 we only expect about 1/3 of a magic item per level, so rounding to the nearest integer, this appears as zero (0) in the table above. At other levels you may get 1, 2, or 3 magic items on average from the Vol-3 random method. If you make a dungeon of 12 levels (~500 rooms?), then we'd expect a grand total of around 14 magic items in the whole complex.

So I think that most of us would agree that simply can't stand; we have to do something else to supply fighters with magic arms and armor, wizards with wands and spell-scrolls, non-renewable potions of healing et. al., and other stuff. The most obvious way is by DM fiat, thinking of the "thoughtfully place" dictum. But then we are left with no other guidelines for what kind of distribution is recommended in that advance process.

Perhaps one faint idea is to shift magic-positive results from one single item to 1d6 at a time (roughly tripling the numbers estimated above, on average). Any other ideas?


Edit: Some folks in the comments take the interpretation that maps should not be generated from that dungeon-treasure table, actual magic only (maps for wilderness treasure only). There's definitely an intriguing case to be made there, but I'm not sure it's ironclad.

On the other hand, if we do permit maps in dungeon hoards, then perhaps we should account for the magic items to which they can lead you. Random maps have a 30% chance of leading to a "Magic Map" table, and 10% to a "Magic & Treasure Table". Those are both d8-based, and coincidentally, they each have an expected production of 19/8 = 2.375 magic items (individual results go as high as 5 items!). So together any random map expects to lead to 0.40 × 2.375 = 0.95 magic item. We might as well round that to "1", which tells us that we can effectively just ignore the map discount itself (each map leads to an average of one magic anyway). Either way, we're then back to an expectation of 1.66 items in the first three levels of the dungeon (not a big difference).

Or taking Daniel Wakefield's idea, maybe that gives us a clue for what a thoughtfully-placed "big magic cache" might be: 1-5 magic items or something like that. Other ideas are to scale it to the expected number of items PCs might have per level (almost embarrassed I didn't think of that earlier).

Consider: These days I roughly assume that pre-generated PCs might have a 1-in-6 chance for magic per level in each of 3 categories. (So: a 6th-level fighter with +1 sword, shield, and armor seems reasonable.) That implies about 3/6 = 1/2 item per level. If one PC level correlates with one dungeon level, and we have 4 PCs, then it suggests we want 4 × 1/2 = 2 items per level (permanent items?). Compare that if we say that random magic finds include 1d6 items (similar to the 1-5 range in the maps), then that multiplies our earlier per-level expectation and get 0.553 × 3.5 = 1.94 ~ 2 items per level. So those figures seem synchronous.

On the other hand, if you have big 8-person parties then you might consider the need to double that again? Geoffrey McKinney's stats for B2 indicate the per-area magic rate at about 80% × 50% × 46% = 0.184. So one of my 40-room levels would expect 40 × 0.184 = 7.36 items, or almost quadruple the figure in the prior paragraph. Hmmmm. At least that gives us a starting upper/lower bound for what we might choose.


32 comments:

  1. That is an interesting find. I had never thought the odds were that low but I guess we generally seem to colour odds in our own favour.
    I think it might be reasonable to scale the treasure according to either the number of players or the number of monsters encountered (if this is the case) as seen in later iterations of the game.

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  2. I’m interested to see someone turbocharge the magic item parts. An average of one magic items in 120 rooms is outrageous.

    Now... who makes a 500 room dungeon?! There are probably fewer than ten in circulation and the people who make them design the treasure too.

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  3. Note that even when you roll "Map" on the Magic/Maps Determination Table there's a 40% chance that the map leads to magic, and that 2.5% of maps (10% Magic, 25% "(already there)") have either #6 Magic (3 Items, No Swords) or #1 Magic (Any 1 Item). In fact, these maps can lead to up to 5 magic items (one a scroll, one a potion).
    So rather than only getting 0.25 magic items, it's more like 0.255 with an additional potential 0.675 magic items if you follow the map and defeat the level 5-6 guardian. So it's 0.93 magic items per Magic, really.

    However, I'm not sure that maps are even intended for the dungeon table in the first place. Note how in Vol.2's Treasure Types it's "Maps or Magic", with distinctions for "any N", "N Magic", or "N Map". Compare with Vol.3's dungeon treasure, where the column is simply "Magic".
    It seems to me that the main purpose of the maps is to have an incentive to travel around more during wilderness adventures.

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    1. I agree with your second point. Maps should be placed only in wilderness treasures.

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    2. That's an interesting interpretation, and I'm trying to get my arms around it. On the other hand, the AD&D DMG (and the evidence I see is Gygax thought this was continuous with OD&D) indicates maps can be found in the dungeon: "Randomly discovered maps are not an overwhelming problem. In the dungeon they can show a route down..." (DMG p. 120). So at least it seems like not an open-and-shut case. (Also I kind of like maps in the dungeon as giving tactical goals and focus.)

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    3. Complicating things further, this dungeon treasure table AFAICT did not make it into AD&D. The TSR1 Solo Dungeon Adventures article uses treasure types when monsters are involved and on the "Magic" table when they aren't, but the remake of that article in the DMG's Appendix A (the only source I've found for dungeon treasure) has you roll directly on the Magic Items Table (and disregards Treasure Types). In other words, unless you hand-place them you won't see maps in dungeons.

      Which is a shame, because maps are cool and AD&D actually has a paragraph on handling random maps in dungeons (tl;dr: use Appendix A).

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    4. Yeah, definitely agreed with that.

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  4. I willing to bet this is another of those situations where the tables presented don't match up to the distributions found in modules of the time.
    My current players are 7th level and having difficulty with a number of creatures due to rolling badly on treasure tables/just plain missing treasure.
    Of course, now they are looking to purchase (or steal) a magic sword from its well known owners, so... "Opportunities for Adventure!"

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    1. I agree. See also under Geoffrey M.'s comment below.

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  5. I do not reward magic items until a bit later in the game, around 5th PC level or so, and even then it is more a matter of researching the (usually mega-)dungeon than just random numbers… for I design most of my settings (10+ years worldbuilding leads to such endeavours).
    I like my players skilled at role-playing creatively out of situations, while combat remains strategical to the bones (hex map for the win!, though square tiling is cool too) and avoidable if possible.
    It is a gray fantasy (as I like to call it) setting, so avoiding conflict through negotiation and knowing you will never be almighty is common sense.
    Even when they so happen to find (or forge) a "firebrand", it is merely '+1', at max. '+2', hardly ever more than that (bĂ´nus applied both 'to hit' and to 'damage', of course).
    So, yes, I guess that is it.
    Magic is rare in said fictional world and, thus, magic items are even rarer.
    Are players offput by it? Not at all!
    They feel it is fair, since it is consistent story-wise.
    And why would it be not so? They outsmarted me (or my monsters and NPCs) quite a few times now.

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    1. I certainly respect that! Maybe I'm biased from what we see in Gygax's published modules, pregenerated PCs, etc.

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  6. Assuming typical party size, how many magic items would you expect per person at the start of each character level? How many are desirable?

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    1. That's a good question. At the moment I'm approximating that as (rounding to the nearest d6 pip) a 1-in-6 chance per level in 3 categories per class. So I'd expect a single magic item (potion?) at 2nd level. And at 6th level a fighter with each of +1 sword, shield, and armor, say (on average). +2 at 12th level. That seems reasonable-ish to me these days.

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  7. Is it heretical of me to think that using Gary's A/D&D modules as examples for dungeon stocking is better than using the fractions and percentages given in the rule books?

    I've been running a poll on dragonsfoot as to everyone's favorite Gygax module. B2 has twice the votes of its nearest rivals (T1 and WG4). Using the Caves of Chaos in B2 (for 1st through 3rd level characters) as an example:

    81.25% of areas have monsters.
    50% of monsters have treasures.
    46.15% of the monsters' treasures include magic (a total of 30 magic items [10% of them cursed]).

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    1. You've hit on an issue that I've really been wrestling with, philosophically, of late. I want to make this exact argument, and this has in fact been called heresy by some players -- in particular, some famous people who played in Gygax's original games. When I pointed out this same thing, it was shrugged off as "What Gygax wrote and what he played were different." (With the argument elsewhere that his published modules were essentially a corruption and moral failing.) So I'm a bit torn on that these days.

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  8. Perhaps in a dungeon context, maps should lead to the aforementioned "thoughtfully placed" treasures? Then the random determination for what type of map and the treasure that it leads to would be directly adding to the treasure contained on that dungeon level, and the only thing left to DM discretion would be how exactly to hide and/or guard it (and even then, the guideline of using a 5th or 6th level encounter as a guardian is provided)

    As for increasing the quantity, maybe when the initial determination of the type of item comes up as a potion, give out 1d6 of them instead of just one? Scrolls already come with multiple spells on them some of the time, if you'd like to make them more rewarding you could smooth out that curve of 1-2-3-7 spells and instead have each spell scroll contain 1d6 spells.

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    1. Another idea is that treasures should be multiplied according to the expected party size, just as you've discussed on other occasions of doing with the number of monsters appearing in dungeon encounters. Then if a party of 5 loots a room with treasure in it, they have a 25% chance of a magic/map result (or five rolls of 5% each, if you prefer). Then by the end of the 3rd dungeon level, they'd average 4 magic items and 1 map. Even if the map leads only to monetary treasure, with a 20% chance of swords, a 5% chance of miscellaneous weapons, and a 5% chance of a wand or staff, odds are decent that someone will have something that can harm lycanthropes, gargoyles, and higher-class undead.

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    2. Those are both interesting ideas, thank you! In particular in reminds that the dungeon treasure table uniquely doesn't give any guidance for scaling it to number of players (as opposed to dungeon monsters, wilderness monsters, and wilderness treasure).

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  9. I'd say RAW, without "placed" treasures, you're better off using dungeon treasure to raise an army to take the items away from groups of men and dwarves in the wilderness than hoping to find them in delves.

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  10. I was inspired to put together a treasure hoard for a wizard's tower assault. The defenders are a lvl 9 wizard and three 10 HD automata called Brass Golems.

    I did the treasure based on how many PCs there are and I made it magic items plus roughly 3,000 GP of money. That is a nice pop for a group of maybe 5th or 6th level guys.

    The prizes:

    Casting implement – Wand of Cold, 50 charges minus what he uses
    3x Potion of Fly
    3x Potion of Healing
    Misc Weapons - +1 Warhammer
    3,000 GP per PC, max 21,000 in this arrangement:
    302 of each coin from PP to EP to CP. The PCs can decide how much loot to lug.
    A gem worth 1,000 GP, one for each character: Amethyst, emerald, citrine, aquamarine, diamond, peridot, lapis lazuli, moonstone


    Are you seeing a big problem with any of this?

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    1. That seems within the realm of reasonable to me, my shading a bit towards the generous side. (I might be skewed right now at low treasure values from the Vol-3 table.)

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  11. Why not look at the NPC population?

    Bandits have a 5% chance per level for three different types of (class related) item (or 1/20). I leave it to the mathematician to calculate the exact number of items per level a bandit can be expected to have. My WAG is to calculate the odds of NO magic items on any given level (that is they flub all three rolls).

    0.95^3 = 86% nada / 14% 1+ items

    So I think you could say roughly that the DM should place at least one special magic item find for every 7 PCs. That will create a magic item density similar to the NPCs.

    A simpler way to do that (which I always like) is to say:
    "The odds of a magic item being thoughtfully placed on any level of the dungeon are equal to 1/6 for every PC in the party. The item will be one that can be used by the characters in question. i.e.,
    Fighters (Armor, Shield, Sword), Mages (Wand/Staff, Ring, Misc Magic), Clerics (Misc Weapon, Armor Shield)."

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    1. That's pretty good, actually. Thank you for that idea!

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    2. I would prefer the 1 in 6 per level that Delta mentioned above as the rate that he currently uses. Dungeon monsters are deadlier than merchants and their guards, so dungeon treasure needs to be proportionately richer or else the PCs might as well just become bandits themselves.

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    3. I would point out that I would roll the 1 in 6 per PC as a bonus in addition to that called for on the treasure tables.

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  12. One more idea to match NPC pops: just place a n appropriate item for each character around level 6 and 12, plus whatever else they find.

    To space it out you could either roll (find an item at level 1d6 and level 1d6+6) or do a certain type of class on each level (example, fighter item s at level 5, rogues at 6,and MU at 7).

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  13. "It is a good idea to thoughtfully place several of the most important treasures..."

    "The most obvious way is by DM fiat, thinking of the 'thoughtfully place' dictum. But then we are left with no other guidelines for what kind of distribution is recommended in that advance process."

    It's hard to remove salt from a boiling stew. If you mainly roll up or place goblins in your dungeon, fewer magic items are necessary than if you have gargoyles. The tables error to the side of not dumping the salt shaker into the stew before knowing what else is in it. Changing the tables assumes a minimum level of needed magic above what was believed the required minimum levels by Gygax and whoever was consulted during the fashioning of that section of the rules. Those "guidelines" suggested you see what is needed then add salt to taste rather than to assume everyone needs more salt in their stews, some stews others have yet to even begin making. It's not fiat to allow the person with the most first hand knowledge to handle such escalations. Still, it's a thoughtful and useful article, nonetheless.

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    1. Hi, Mark -- On this site we're usually looking to quantify things a bit more than "the DM gets to decide", esp. for core book rules. E.g., "what was believed by Gygax" gets pretty messy when we look at B2 (above) or other adventures and see how different it was. Etc.

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  14. Treasure Dungeon Stocking throughout the ages?

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