On Long-Lasting Spells

An Elegant Rule for Maximum Durations

At some point I suppose I should update & revise my OED Book of Spells product, based on gameplay lessons over the last 5 years or so (but it's pretty hard to know when to make the call on that). Among the things I'm getting to take a closer look at are the durations for various spells; the ones that elapse in one encounter are not so critical, but there are a number of spells that may last for a day, or months, or permanently -- and they tend to vary wildly between editions (particularly in 3E that my book was based off), so I'd really like to get those right. Recently, some have started to bother me in my games; but the table I recently made for "Spells Through the Ages: Duration Redux" (link) should help give a comprehensive assessment of the situation.

For starters, one of my great pet peeves are low-level spells with permanent duration. I totally grind my teeth at the prospect of minor wizards wandering through the campaign world and trollishly wizard lock-ing, continual light-ing, continual darkness-globing, and magic mouth-ing every site they wander through, for all eternity (for spite!). So one of the rules I implemented for Book of Spells is that no spell under 5th level can be permanent (those being the ones gained around name-level for wizards, spells that really need to be long-lasting to serve their vision in the game). And I've never regretted that.

Now, I think at this point I might be able to develop an even more general guiding principle for long-lasting spells in my game. Let's look at a list of classic D&D spells that have unusually long-lasting durations, and compare across durations:
  • Charm Person (1st level) – We start with an epic outlier. Duration is "Special" (recurring save schedule based on Intelligence: maybe daily, weekly, or monthly) in Editions 0-1-2-BX. Greatly reduced to 1 hour/level in 3E.
  • Continual Light (2nd) – Permanent in all editions.
  • Magic Mouth (2nd) – Permanent until discharged in all editions.
  • Strength (2nd) – 8 hours in 0E (Sup-I). 1 hour/level in 1-2-3. Not in BX.
  • Wizard Lock (2nd) – Permanent in all editions.
  • Infravision (3rd) – 1 day in 0E-BX. 2+level hours in 1-2. 1 hour/level in 3E.
  • Suggestion (3rd) – 1 week in 0E (Sup-I). Approximately 1 hour/level in each of 1-2-3. Not in BX.
  • Water Breathing (3rd) – Highly variable: 12 turns in 0E. 3 turns/level in 1E. 1 hour/level+4 in 2E. 2 hours/level in 3E. 1 day in BX.
  • Charm Monster (4th) –  "Special", similar to charm person (but with weekly chances to break based on Hit Dice) in 0-1-2. In BX, identical by reference to charm person. In 3E, reduced to 1 day/level.
  • Hallucinatory Terrain (4th) – Permanent until touched in Chainmail-0-1-BX. 1 hour/level in 2E. 2 hours/level in 3E.
  • Plant Growth (4th) – Permanent in all editions. Note 3E has an optional usage for "enrichment" lasting 1 year.
  • Polymorph Other (4th) – Permanent in all editions.
  • Polymorph Self (4th) – Not a long-term spell until 3E. 6 turns+level in 0E-BX. 2 turns/level in 1-2. Increased to 1 hour/level in 3E. 
  • Passwall (5th) – Another non-long term spell until 3E. 3 turns in 0E-BX. 6 turns+level in 1-2. Increased to 1 hour/level in 3E.
  • Control Weather (6th) – Not specified in 0E. Concentration in BX. 4d6 hours in 1-2E. 4d12 hours in 3E.
Among the things you see above are the rather absurd – to my mind – number of spells at the 1st-2nd levels that are permanent or indefinite in duration (charm person, continual light, magic mouth, wizard lock). Another thing is that almost all of the long-lasting spells at 4th level are permanent (excepting only polymorph self), which to my mind is borderline at best. Also note that I omitted the various 5th-6th spells that are basically permanent across most editions (animate dead, feeblemind, magic jar, transmute rock to mud, wall of iron, wall of stone, geas, invisible stalker), with which I don't have much problem.

But once you clear out those troublesome cases from the list above, a pattern starts to emerge, which I might interpolate and express along these lines for maximum possible duration:

  • 1st level – 1 day.
  • 2nd level – 1 week.
  • 3rd level – 1 month.
  • 4th level – 1 year.
  • 5th-6th level – Permanent.

Now, if I iron out the spells in my game according to these guidelines, here are the changes I would make. First, that 1st-level outlier with the unique recurring save schedule, charm person, gets reduced to 1 day (about what 3E did). This seems pretty reasonable to me, as the spell commonly seems overpowered (in fact, if I do some solo play, this is usually how my PC gets taken out of the game – regardless of level); you can still get a long-term charm with the higher-level spell (below). At 2nd-level, those too-soon-permanent spells continual light, magic mouth, and wizard lock become 1 week (just as I did in Book of Spells previously); strength remains 1 day since it's so useful (approximately the same as any prior edition).

At 3rd level, I'll keep infravision and water breathing at 1 day because they're so potent (like in BX), but I think I'll actually expand suggestion to a 1 month duration because that always seems under-used, and I thereby get to exemplify each step of my general rule above. 4th level is where you get the borderline cases (traditionally permanent but not at the 5th level where I want them) – I think that capping charm monster, hallucinatory terrain, plant growth, and polymorph other at a 1 year duration has a very fairy-tale feel to it (compare: the dryad charm power in 1E has a year for its unit; and plant growth in 3E has the 1 year usage built in, too); polymorph self, of course, can be very powerful and should remain at the early-edition duration of just a number of turns. For simplicity, I'll probably make the dominating control weather at the 6th level last 1 day (as I did previously).

I think that general guideline works out very well. I'm very comfortable with the solutions that gives me to the lower-level 1st-2nd level spells, and even pretty jazzed at the flavor of the 4th level spells lasting for 1 year.

But let me conclude by asking a possibly deep question: What about those other 5th-6th level spells that I've left as Permanent – does Permanent really mean Permanent? Extrapolating our model of max-possible durations here would seem to imply that even those spells should wear off after some number of decades or centuries. Perhaps the DM should secretly interpret those spells as having limited durations as well, merely beyond the ken of a man's lifetime, such that no man or woman has ever noticed their ending? What prospects does that hold for your campaign game if there are long-lasting feebleminds, magic jars, walls of iron and stone, invisible stalkers, and armies of animated dead out there in the world whose time is ticking towards an end?


  1. agreed..
    permanent = 1 decade per level of spell caster...
    real world corollary most documented 'hauntings' last less than 200 years

  2. How about having the 'permanent' spells last until the same spell is cast again? Continual Light lasts until another Continual Light is cast. Perhaps a spell caster could have as many 'permanent' spells in effect as they have spells of that level. A fourth level M-U could have two 'Wizard Locks' in effect at any one time.

    1. Hmmm, interesting. For me that might clash a bit with the Vancian math-formula conception. But pretty good game balance.

    2. This (a magic-user only gets one continual light at a time) is exactly what I do and it works swimmingly.

      Delta, I actually think this fits conceptually very nicely with Vancian spell casting. When the magic-user casts continual light (or whatever), they take the magic out of their head and put it somewhere else. When they prepare the spell again, they retrieve that thing that they left.

  3. What I did in this situation was to say that if a spell is still operating, then that spell slot can't be used, it's tapped out. So, in effect, a character gives away a first level spell slot as long as the charm, for example, is working. I've greatly increased the number of spells that last forever doing this: light, shield, tensors floating disk, invisibility, etc.

    As for permanent, spells end when the caster dies. This way you can use the collapsing wizard tower trope.

    1. Also interesting. I'd certainly prefer the cleanliness of that rule to a brand-new limit to be managed (above).

  4. Very interesting, and also Hedgehobbit and Zenopus' suggestions, thanks. Continual light is the one that has long rubbed me the wrong way.

    1. Me too. Initially I thought the 3E "continual flame" change (fake torch) was clever, but it lost the charm for me over time and now feels clunky.

    2. Scientist: "It's my greatest invention! Room temperature fire!"

      The Tick: "Good Lord, man, what's the point?"

    3. LOL. What a great era for cartoons. :-)

  5. Interesting. Would you be willing to allow lower-level spells to be cast as if they were higher level in order to get longer durations? Burn a 4th-level spell slot to cast Wizard Lock and it lasts a year; get rid of Continual Light and just have Light last longer the more power you put into it. That addresses the "low-level wizards running around putting permanent marks on the world" issue while also giving players some more options and flexibility.

    Also, what do you think of the Permanency spell some editions have?

    1. Good question. One thing I'm rewriting in my game is extension (4th level) to let any lesser turn-based spell switch to lasting 1 day. So modifying durations with other magic seems well-themed for me, and I'd be okay with permanency as long as it's at least 6th+ level (and of course it's 8th level when it does appear). It also makes sense that it usually has a restricted list of spells: haste sticks out as a dangerous option for extending duration, there might be others.

  6. I would like to petition that we extend Permanent spells to lifetime of the cast +50 years, 75 years in the case of spells cast with sponsorship of the Throne. You see, families and kingdoms depend on these spells for their well being and will encourage Mage's to cast their own permanent spells rather than rely on the work of others. :)

  7. I like my rules to make sense "in real life" from the perspective of the inhabitants of the campaign world. I don't have any problem with some spells being permanent, otherwise those ancient tombs and dungeons and stuff would be unlit, with no magic mouths, "dead" undead, etc.

    Having said that, whatever rules we determine for the way these spells work has an impact on the world. If continual light/continual flame is such an easy spell to cast, then certainly the standard form of lighting in any city would be a wooden "candle" with a lid to darken it at night.

    I think it's helpful to extrapolate the effect to the world as a whole than just the impact on the PCs in the context of their adventures/combat.

    This is why I really enjoy in-depth looks at the rules like this, because I hadn't even considered something like continual light/continual flame yet. Now it highlights a glaring contradiction between a simple spell and Waterdeep's Guild of Chandler's and Lamplighters which is entirely unnecessary with that spell.

    I don't like the idea that casting it again snuffs an earlier casting. Too "quantum magic" for me. But the idea of permanent low level spells is one that is likely to go.

    More changes to make...


    1. I do think it (more) helpful to look at it in the other direction -- What kind of campaign world do we want to support, and therefore, what restrictions on the magic must exist? I'm not fond of one glitchy spell description changing the entire world away from what we wanted. Better to assume a fix to the spell. E.g., see "Gygaxian Perspective" at the end of the article here.