Spells Through The Ages – Transmute Rock to Mud

Bearded man in mud up to shoulders
Let's say you have a formerly firm establishment and you want to collapse the whole thing; your preference to have it be a big sludgy morass instead. Degrade your opponents via a real mud-slinging contest. How to do that? Well, of course: transmute rock to mud is your huckleberry.

Original D&D 

Transmute Rock to Mud: The spell takes effect in one turn, turning earth, sand, and of course, rock to mud. The area affected is up to 30 square inches. Creatures moving into the mud will become mired, possibly sinking if heavy enough or losing 90% of movement otherwise, unless able to fly or levitate. The spell can only be countered by reversing the incantation (requiring a Transmute Rock to Mud spell) or by normal process of evaporation (3-18 days as determined by rolling three six-sided dice). Range: 12".
This spell was not ever included in Chainmail Fantasy -- which is a bit surprising, because to my eye it looks tailor-made for an outdoors mass-combat use case. (Compare to: move earth, et. al.) So we start with Original D&D (5th level spell); as shown above, the primary thrust of the spell seems to be in creating a large muddy field to obstruct the progress of one's enemies. While a surface area is given, no depth is mentioned; so it might be unclear whether victims can possibly drown or not.

The duration is a little unusual for two different reasons. One is that it is the first magic-user spell in the game to imply that it can be "reversed" to create its opposite effect. There is no general rule for this in OD&D; and in fact it is only one of two such magic-user spells which allow that (the other: stone to flesh at 6th-level). This is in contrast to about half the spells on the clerical list which are underlined, indicating that they are (automatically) reversed by evil clerics.

The second oddity being the fact that over many days the effect may just wear off naturally; I don't think that there's any other spell in the game that functions likewise. In the Swords & Spells master table, the duration is listed as "full game".

Expert D&D 

Transmute Rock to Mud
Range: 120'
Duration: 3-18 days

This spell changes a volume of rock up to 3,000 square feet and 10' deep, to a morass of mud. Creatures entering the area of mud may be mired and are slowed to l/10th of their normal movement speed.

The reverse of this spell (transmute mud to rock) changes up to 3,000 square feet of mud (10' deep) to rock. The effect of this reversed version is permanent.

Cook's version in Expert D&D is almost identical. The 3-18 days duration here would most likely be interpreted as a (very weird, very random) duration for the magic itself, not an effect of natural evaporation. The effect on earth and sand is not mentioned. Cook does give a depth figure for the first time -- a fixed 10', so one might think that drowning is a possibility, but the effect otherwise specified seems to only indicate slow movement (swimming?).

Note that Expert D&D does have a general system for reversal of both magic-user and clerical spells,  indicated by an asterisk in the spell rosters -- many such clerical spells are given (as above), but still fairly few magic user spells (6 spells out of a total of 72 by my count).

AD&D 1st Edition

Transmute Rock To Mud (Alteration) Reversible

Level: 5 
Range: 1"/level 
Duration: Special 
Area of Effect: 2 cubic "/level
Components: V, S, M
Casting Time: 5 segments
Saving Throw: None

Explanation/Description: Except as noted above, and that the material components for the spell are clay and water (or sand, lime and water for the reverse), this spell is the same as the fifth level druid spell, transmute rock to mud.
The druid spell description saying this:
Explanation/Description: This spell turns natural rock of any sort into an equal volume of mud. The depth of the mud can never exceed one-half its length and/or breadth. If it is cast upon a rock, for example, the rock affected will collapse into mud. Creatures unable to levitate, fly, or otherwise free themselves from the mud will sink and suffocate, save for lightweight creatures which could normally pass across such ground. The mud will remain until a dispel magic spell or a reverse of this spell, mud to rock, restores its substance - but not necessarily its form. Evaporation will turn the mud to normal dirt, from 1 to 6 days per cubic 1" being required. The exact time depends on exposure to sun, wind and normal drainage. The mud to rock reverse will harden normal mud into soft stone (sandstone or similar mineral) permanently unless magically changed.

We see that as in Cook's work, the effect on non-rocky earth and sand seems to be removed. The area is now actually a volume, variable by level (as for most spells in AD&D), and the depth is now an algebraic calculation based on min(length, breadth)/2, subject to available volume. Sinking and suffocating are explicated for the first time. Evaporation is now made even more vague for the DM ("depends on exposure to sun, wind and normal drainage"; I prefer the flat 3d6 roll if we must do that). A description of the effect on a single discrete "rock" is given for the first time, as well.

The DM's Guide gives this additional errata/information:
Transmute Rock To Mud:  Rate of sinking is  1'  per segment, i.e.  1'  per  6 seconds or  10' per minute (round). Brush thrown upon the surface will stop sinking of creatures able to climb atop it (use discretion  as  to the amount of brush and the weight of creatures). Ropes can be used to pull creatures out of the mire, assuming that sufficient power  is  available  -  1 man/man, 10 men/horse (or vice versa).

In 1986 Doug Niles' Dungeoneer's Survival Guide included a section on running Battlesystem engagements in the depths of the underworld (recall that Niles was himself the author of the well-received Battlesystem supplement for D&D). In a subsection on "Cave-ins On A Battlefield", he writes (p. 35):
Spells such as earthquake and transmute rock to mud are commonly used for this purpose. If a ceiling collapses, the area affected on the ground is the same as the area of the ceiling collapsed, plus 1" in all directions. Such a collapse does 6d8 hit points of damage to all creatures in the area of effect; a saving throw vs. spell reduces the damage to half. Thus, an orc figure representing 10 orcs suffers 60 dice of damage, and is automatically destroyed whether it saves or not.

A similar weight of mud falling on a unit inflicts only  4d8 points of damage, again halved if a saving throw is successful. 
While that's a logical extrapolation of the spell's effect, I'm not sure that I'm entirely satisfied by that. More on that thread below. 

AD&D 2nd Edition

Transmute Rock to Mud

Range: 10 yds./level
Duration: Special
Area of Effect: 20-ft. cube/level
Components: V, S, M
Casting Time: 5
Saving Throw: None

This spell turns natural rock of any sort into an equal volume of mud. The depth of the mud can never exceed half its length or breadth. If it is cast upon a rock, for example, the rock affected collapses into mud. Creatures unable to levitate, fly, or otherwise free themselves from the mud sink at the rate of 10 feet per round and suffocate, except for lightweight creatures that could normally pass across such ground. Brush thrown atop the mud can support creatures able to climb on top of it, with the amount of brush required subject to the DM's discretion. The mud remains until a dispel magic spell or a reverse of this spell, mud to rock, restores its substance--but not necessarily its form. Evaporation turns the mud to normal dirt, at the rate of 1d6 days per 10 cubic feet. The mud to rock reverse can harden normal mud into soft stone (sandstone or similar mineral) permanently unless magically changed.

The material components for the spell are clay and water (or sand, lime, and water for the reverse).
This is mostly another copy-and paste job from the 1E text, with the detail from the DMG about sinking rate and use of brush for floatation inserted. The duration is again given as due to evaporation, but the factors affecting that in 1E are removed, at least for the wizard version -- in the alternate priest spell, it is still there ("The exact time depends on exposure to the sun, wind, and normal drainage.").

D&D 3rd Edition

Transmute Rock to Mud

Level: Drd 5, Sor/Wiz 5
Components: V, S, M/DF
Casting Time: 1 action
Range: Medium (100 ft. + 10 ft./level)
Area: Up to two 10-ft. cubes/level (S)
Duration: Permanent (see text)
Saving Throw: See text
Spell Resistance: No

This spell turns natural, uncut or unworked rock of any sort into an equal volume of mud. Magical or enchanted stone is not affected by the spell. The depth of the mud created cannot exceed 10 feet. Creatures unable to levitate, fly, or otherwise free themselves from the mud sink until hip- or chest-deep, reducing their speed to 5 feet and giving them –2 penalties on attack rolls and AC. Brush thrown atop the mud can support creatures able to climb on top of it. Creatures large enough to walk on the bottom can wade through the area at a speed of 5 feet.

If transmute rock to mud is cast upon the ceiling of a cavern or tunnel, the mud falls to the floor and spreads out in a pool at a depth of 5 feet. The falling mud and the ensuing cave-in deal 8d6 points of damage to anyone caught directly beneath the area, or half damage to those who succeed at Reflex saves.

Castles and large stone buildings are generally immune to the effects of the spell, since transmute rock to mud can’t affect worked stone and doesn’t reach deep enough to undermine such buildings’ foundations. However, small buildings or structures often rest upon foundations shallow enough to be damaged or even partially toppled by this spell.

The mud remains until a successful dispel magic or transmute mud to rock spell restores its substance —but not necessarily its form. Evaporation turns the mud to normal dirt over a period of days. The exact time depends on exposure to the sun, wind, and normal drainage.

Here's the 3rd Edition version of the spell; longer (as usual), but mostly the same -- in terms of volume, duration, use of brush, evaporation, and factors effecting evaporation (most of that copied forward from the 1st Ed rules). In the standard 3rd Ed. safety-bumpering, the possibility of suffocation (seen in 1st-2nd Ed.) has been removed, and victims can at most "sink until hip- or chest-deep", even though no rational mechanic for that is given.

But probably the most important changeover the entire evolution of the spell happens in the first line here: it is limited, for the first time, to working against "natural, uncut or unworked rock". That's a pretty big change, whose details are spelled out in the 3rd paragraph. We might think that a pretty common-use case is for a band of heroes or villains to be confronted by an opposing keep and think: "Hey, that castle's stone. If we just cast one transmute rock to mud, that whole gatehouse will just collapse, right?" In the 1E era, I definitely thought that was the implication, even though it was never specified in any version of the spell; here that is prohibited due to the "unworked" clause.

I actually really like that limitation to the spell. In fact, I'm kind of befuddled as to why that was never addressed in any earlier edition. Separately, there's the also the detail in the 2nd paragraph about collapsing the roofs of underworld tunnels and causing 8d6 damage cave-ins (save for half); this seems very reminiscent of Doug Niles' rule in the 1E Dungeoneer's Survival Guide, but it's unclear if the rule was imported directly from there. At any rate, I'm not sure I like that so much.

Gygaxian Perspective

Let me expand upon that issue in its own section. What would Gygax's intent be regarding transmute rock to mud against stone fortifications? For starters, the overwhelming evidence is that Gygax conceives of the standard D&D game world as being essentially quasi-medieval in nature, and I support that. Radical changes in the game world society cannot be inferred from one or two whacked-out spell descriptions; rather, if a certain magic effect inherently contradicts the medieval world situation, then something about the spell needs to be adjusted to comply with that initial assumed milieu. (OD&D Vol-1, p. 5: "expansion is recommended only at such time as the possibilities in the medieval aspect have been thoroughly explored").

For example: Gygax's second novel, Greyhawk Adventures: Artifact of Evil opens with a major assault on a concentric stone castle at the edge of the Pomarj (a region overrun by evil humanoids; setting of the A1-4 Slave Lords series of modules). In addition to legions of men and monsters, fairly large contingents of spell-casters are engaged on both sides of the battle. From the first paragraph of the book:
The starless night was suddenly bright with globes of glowing light, radiance that shed betraying illumination behind the lines of besiegers outside the fortress... The magic missiles, blazing fireballs, and crackling bolts of lightning were far worse. Bodies were tossed high by roaring blasts; wheeled shelters were split and broken by the flashing strokes of electricity while metal-clad men-at-arms behind them became charred corpses. Varicolored darts sped unerringly into hapless targets who screamed and died. Torrents of flame erupted from the sky to set siege towers blazing, giant torches that added a hellish light to the scene, while raging fires swept over the advancing lines or made curtains of flame that seared their flesh.
Other magic effects that are thrown from either side over the course of the next few pages: summon elementals (fire), Evard's black tentacles, chain lightning, cone of cold (?), darkness, moonbeam, precipitation, cloudburst, summon elemental (water), summon elemental (earth), major illusions, etc.

That's a lot of high-level magic. But one thing that doesn't happen: at no point are the walls of the castle transmuted from rock to mud. That's hard to interpret if Gygax thinks the effect is feasible, in the context of such an enormous force of high-level spell-casters. Likewise: Note that the 1E DMG had a table including about 10 magical effects that would cause structural point damage against constructions in a siege (p. 109), but transmute rock to mud was not among them.

More evidence from the old Gygax Q&A thread on ENWorld (dates uncertain): One poster proposes a plan of action in regards to the famed Temple of Elemental Evil: "One mage with a Rock to Mud could take out the whole place..." (going on for about 9 paragraphs about the detail of volume of mud involved , effect on lower levels, etc.). Here's Gygax's response:

My players know better than to try something sure to incur wrath >:-)

Such tactics are a matter for the DM to manage, and as one here is how I would handle an attempt of this sort.

"Sorry, Flubspell, but your Rock to Mud casting seems to fizzle out when it contacts the stonework of the temple. golly, I guess the builders must have imbued it with some fort of protection from this sort of assault on its integrity..."

"Oh, by the by, it seems that you are now turning a ghastly gray color. It seems as if yout attempt has invoked a curse of some sort, as you feel quite weak and not at all well..."

I'd use the same sort of response if someone tried that with any important campaign setting. To stop the rules lawyers from their shrill protests I's write up a few spells to cover constructions--anti-disintigration, anti-rock to mud, etc. Also a few retributive spells to be activated and aimed unerringly at any spell caster attempting to bring down a stricture by that sort or obvious and predicatble tactic. Just because such spells are not included in the standard roster doesn't mean they don't exist.



So as expressed earlier, Gygax does not look at a spell like transmute rock to mud and deduce that medieval stone fortifications are passé in the D&D campaign world. Rather, he takes as a given that castles exist in the game (and dungeons!) and instead extrapolates that there must be a rather wide array of protection and "retributive" spells commonly used upon such constructions. Not just for the Temple of Elemental Evil itself, but explicitly "any important campaign setting", which I would argue would include any fortification set down by the DM in the campaign world.

I think all of that comes from an honorable instinct. The one thing on which I tend to differ with Gygax is that the implied array of defensive spells (outside any rulebook) seems to commit the offense of "multiplying entities beyond necessity". I would prefer a more minimalist solution, by simply adjusting the originally offending spell a slight bit -- and I think (somewhat unusually) that the 3rd Ed. limitation to "natural, uncut or unworked rock" is a pretty elegant piece of editorial wisdom. I even take an extra step in my own Book of Spells and further prohibit use of the spell against any "load-bearing" stone, so as to cut out the tunnel (and dungeon) cave-in usage.

May I also point out that Gygax's sarcastic reference to the transmuter "Flubspell" here (sometime in the early 2000's), is reminiscent of a character identified as "Flubbit the Wizard" back in OD&D Sup-I (1976; see the magic mouth spell description on p. 22). 


Which form of the spell is your favorite? Did you actually prefer more chaos in your world, such that that transmute rock to mud works on fortifications and makes them effectively a useless piece of technology?


  1. My instinct on the use of the spell on worked stone or fortifications would be either:
    1) place a greater limit on the area of effect of the spell (allowing it to be used to make breaches or tunnels for only a handful of people at a time, but not to collapse an entire building or wall) or
    2) remove the spell.

    Limiting the spell to creating difficult terrain kills its excitement (although editions that allow it to be used to suffocate/drown foes make up for this) and remove the best feature of the spell. Honestly, when I first came across it, I thought burrowing through structures and fortifications was the spell's raison d'être in the first place. :)
    (Related: many standard fantasy settings seem to portray wizards as too common. Mundane wizards - common enough that any besieging army would bring several - defeat the whole point of wizardry, haha.)

    1. The one thing I would say about expecting transmute to do tunneling work is that it would seem to make "passwall" at the same level defunct.

      I do remember being surprised at the number of spellcasters present at the start of Gygax's novel, noted above.

  2. My instinct is to start with the 3rd edition, then simplify it. I go back and forth on the "collapse" feature, it is a 5th level spell and could be a good bang for your buck.

    It is interesting to see the push and pull of trying to maintain a mostly medieval world while acknowledging the consequences of magic and fantastic beasts. As well as the arms race of spells and counters/creative players over the editions.

  3. Hmm...for whatever reason, I think I always interpreted the spell (or "mis-remembered" it) as only functioning on unworked stone. Maybe the words "natural stone" in the 1E description put this in my mind. Regardless, the spell never saw much use in my games, perhaps because the text implied it's main utility was to mire and slow opposition.

    [the old AD&D comic book from DC had a rather amusing scene where an evil wizard uses "flesh to stone" and follows it up with "rock to mud." I always thought it would be badass to pull that on a PC]

    I think my opinion really depends on the relative scarcity of magic in the campaign. If there's a noticeable lack of wizards capable of casting such a high level spell, I would probably allow the wider latitude of use (bringing down castle walls, etc.). Such an individual would be rightly feared...and despised and hunted by the local nobles should he (or she) exercise such power too often.

    Yeah...the more I think about it the more I like it.
    ; )

    1. That's a good observation about the 1E "natural stone" language; maybe I overlooked that a bit.

  4. A typical 9th level Fighter will have a modest castle, maybe just a single walled compound with a keep inside. For a caster of 9th level to be able to totally negate that is a bit much. Especially with the Druid version, making it applicable only to natural stone seems cool. But how about making a distinction between contiguous stone (like bedrock, or a cave) like with Meld Into Stone. This does a couple things:
    1: A Wizard casting Wall of Stone to create cheap fortifications for the Fighter is not only leaving him open to Dispel, but also Meld Into Stone, Transmute Rock to Mud, etc.
    2: Fighters who go through the expense and time to build a castle can enjoy security that it will take several dozen spells to create a small breach in a wall.
    3: It doesn't change the spell's ability to affect the ground - as long as it's solid stone such as in a mountainous area or underground on bedrock.

    The big downside I can see is that it doesn't affect gravel, sand, etc. on a battlefield. But maybe that's good - some spells are useful in forests and grasslands, others on bare stone, some terrains are safe, etc.

    1. Hmmm,that's interesting, I may have to think about that. A intriguing game-design problem; is it thematically really better to have transmute rock to mud be working on man-made, or non-man-made objects?

    2. It took me a moment to understand what 1d30 was going for here. But I think I get it:

      A fortified wall is built of separate pieces of stone, and therefore the spell only affects one of them. Very interesting (and clever) solution.

      It's funny, because I was thinking of almost the opposite solution--that large expanses of stone are too MUCH mass to be affected. Much like the difference between trying to boil a cup of water vs 5 gallons of water. You need a much bigger fire.

      It's easy enough to say that even on an area of bedrock, there are cracks and sections within the rock.

      Then I did some math:

      If we go back to the AD&D 2 cubic feet per level, but use the 5e spell slot level as the measure, then the most you can get is 18 cubic feet as a 9th level spell. That's about the size of a small refrigerator. Hardly castle-threatening. Even with the caster level, a 20th level caster making 40 cubic feet is only about 2 of those refrigerators. Depending on how many spell casters you have capable of 9th level spells, I don't consider it a real issue.

      Cook isn't anywhere close to identical.

      OD&D indicated 30 square feet, and Cook gave 3,000 square feet. That's a HUGE difference. Cook describes 3,000 cubic feet.

      That's a difference between 3' x 10' and 300' x 10'!

      I'd consider Gygax's 2 cubic feet as closer to what he meant by 30 square inches (since he wrote both the OD&D and AD&D versions). As a 5th level spell, you'd be 9th level minimum to cast it, or 18 cubic feet. That's about the size of a small refrigerator.

      2nd Edition and later described 20-foot-cubes (way different than 20 cubic feet). Again, it seems to be an issue with the TSR guys understanding math.

      30 inches by 10 inches, by 10 feet deep is 20 cubic feet (and possibly Gygax's original measurement - that's an inherent problem in using "inches" to measure feet or yards, or sometimes just inches).

      A 20 foot cube, on the other hand, is 8,000 cubic feet. At 9th level it's 18 20' cubes (which really makes the math more difficult), or 20' x 20' x 360' or 144,000 cubic feet.

      The problem here is the lack of game designers understanding their math - not the spell itself.

    3. I think the main thing you're overlooking is where the early text says "inches" (or the symbol "), meaning an in-game scale of 10 feet each.

      E.g., The OD&D text actually says "30 square inches" (not feet). A square inch means 10'×10' = 100 square feet; so the spell affects 30 × 100 = 3,000 square feet; which is identical area to Cook. Note also that the 10' depth of Cook creates a 3,000 × 10 = 30,000 cubic foot volume.

      Likewise, the AD&D specification is 2 cubic inches (not feet) per level, indicating a 10×10×10 foot volume for each of those "cubic inches". At 15th level you get the same volume as in Cook, say. The 2E specifier is trying to say the same thing (arguably off by a factor of 4).

      In conclusion: The area/volume is quite large and pretty consistent throughout early D&D.

    4. Doh! That's why you're the math lecturer and I'm not!

      Except that I would translate that 30 square inches into 300 square feet.

      12" = 120'
      30" = 300'

      So it's still smaller than a factor of 10. At least the way I would read it, as 300 square feet (or 30 x 10 feet) which is quite a bit less.

      Likewise I would read 2 cubic inches as 20 cubic feet. Which makes sense since later on they equated that to a 20' cube (which as I've shown IS mathematically incorrect - unless I'm wrong again...which is quite possible. Probable if you saw my math grades!).

    5. Area in square units has two dimensions, not one. Area of a square is given by A = s^2. So if one linear inch is 10 feet, then a square inch is (10)^2 = 100 square feet.

      Compare: Converting Between Square Yards and Square Feet (video).

    6. OK, now I think I get it. And I'll post this only because it might help somebody else who doesn't get it.

      Here's the way I read it:

      When D&D lists 3" it really means 30 feet (or 30 yards sometimes). It's not really a math conversion, it's shorthand.

      So when it says "30 square inches" I read that as "300 square feet" because the shorthand multiplies the number by 10 and replaces the word inches with feet.

      So the spell, to me, affects 300 square feet. Which is considerably less than 3,000 square feet.

      The same thing with the 2 cubic inches. I'd equate that with 20 cubic feet.

      But what you're saying is:

      1 square inch in D&D is 10'x10. So when it says "30 square inches" you are saying they mean thirty of those 10'x10' cubes.

      That is a significant difference in size, and now I also understand how 2e came up with the 20'x20' cube description.

      Obviously, the 2e approach of identifying the number of cubes is much easier than calculating cubic feet for people like me, especially when it's also written in shorthand.

      So I guess the answer in my case is that the spell is not as powerful in my campaign as yours, since it covers a much lower AoE!

    7. Yes. But note that this is not an isolated D&D thing. It's just what "square anything" means anywhere (e.g., video lesson above).

  5. "I even take an extra step in my own Book of Spells and further prohibit use of the spell against any "load-bearing" stone, so as to cut out the tunnel (and dungeon) cave-in usage."

    Every stone is 'load-bearing', if a man stands on the stone it's also that. This makes the spell pretty much useless. All I see here is another limitation attempt against mages to make non-casters more powerful compared to them, or in worse case a GM attempt of limiting players trying to avoid traps/dungeon routes by clever planning and spell use.

    1. I think one can reasonably differ about whether this is a great fix or not. But I'm prone to not call obvious, time-worn, cliched spell uses as "clever".

      Coincidentally, I just got an email the other day inquiring what I thought of Gygax's very complicated response to why using it on the Temple of Elemental Evil wouldn't work. Personally, I think simple solutions like this are the best way to prevent setting-destroying side-effects.