I've a plan for an adventure that I think would be interesting, but the idea depends on it being possible for certain spells to be learned and memorised without the mage in question gaining insight into some or all of what the spell does. (Presumably casting it and measuring its effects would provide a clue, provided that those effects were reasonably obvious.)

Unfortunately, I'm not sure if this is possible; As far as I'm aware, the process of reading a spell gives a wizard enough insight into its workings that they automatically have a good idea what it does. I'm hoping that there's an established exception to this that I'm not aware of: A published spell with certain important features that most casters don't know about, for instance, or a spell with a hidden side effect that most magic-users overlook. (I could, of course, declare that such spells exist by GM fiat, but I like to use such obviously arbitrary-but-plot-convenient declarations sparingly.)

So, am I in luck?


3 Answers 3


In fact, there is nothing in the rules that says you have to tell the player everything about the spell. It's unusual to omit the basic function, sure, but it's fine to let the player find out that a light spell, for example, causes sunburn after a while. And, in fact, the 1e DMG had a whole section detailing "secret" effects or details of many spells in the PHB.

The classic example from 1e is the permanency spell which the PHB says costs 1 CON to use. The DMG informs us that in fact that's only if used on living things, otherwise there's a save of 2+. We're also told that a magic user can pass through their own Wizard Locked portals freely, and that Dig does substantial damage to clay golems, and many other effects/details.

  • \$\begingroup\$ I was hoping for a 2e-specific example, but my understanding is that 2e and 1e were so close as to make practically no difference. This is useful. \$\endgroup\$
    – GMJoe
    Feb 24, 2015 at 0:05

This is totally legit. If you're running a serious game, just let your players know that they don't know how the spell works beforehand (e.g. "The spell's magic is strange. It seems like it's probably an offensive evocation of some kind, but you aren't quite sure what the expected energy output will be like, nor why it has so many cross-dimensional junctions. You can use it, but your not entirely sure what it will do"), so as not to violate group expectations in a bad way (and also to keep with Wizard spellcasting fluff). If you're running more of OD&D-inspired magic-is-just-silly-sometimes campaign this stuff is pretty much the norm, and doesn't need any explanation.

In addition to having run this in my own games (they went fine), and having played in games with this kind of magic prevalent (they went fine except for the times when all spells worked this way, which was extremely frustrating for everyone involved), it is also an important component of the A Spell Called Catherine campaign and modules EX1 and EX2 for AD&D 1e ("Dungeonland"). The modules are copyrighted so I can't go into too much detail but, basically, casting certain spells in certain rooms causes-- presumably unexpected-- side effects.

A Spell Called Catherine is suitable for serious play. Dungeonland is suitable for Hilarity Ensues.

  • \$\begingroup\$ A Spell Called Catherine is an interesting example to choose, now that you mention it... In some ways, it's a homebrew version of I was asking for: Magic that apparently works completely differently to how its casters thought it did. On the other hand, it's also an example of why I'm trying to find an established precedent for this sort of thing: ASCC is considered controversial by many players precisely because it contradicts established descriptions of how magic works. Hmm... \$\endgroup\$
    – GMJoe
    Feb 24, 2015 at 0:21


This option isn't set explicitly in the rules, but it can be added by introducing more mysterious forms of magic, like Artifacts, whose powers aren't initially clear. However, be careful to avoid making your players feel powerless by changing the consequences of their choices in the system without warning.

Full Answer

This isn't a question of "can spells do other things". Of course they can, even if there isn't anything explicit in the rules about this. This is a game of imagination set in a fantasy world, and spells can do as much or as little as you want, in addition to what it says in the rulebook. You could say, for instance, that Fireball and similar spells will slowly char the wizard's skin, or that necromantic spells could cause it to rot. All this is entirely within the realm of possibility for magic, especially in older editions, like the one you're playing, that haven't entirely entered the "rules are sacrosanct" mentality of 3e and newer editions.

However, what I would worry about here is players feeling cheated of their agency. The rules are there to give all the players a shared set of expectations, and unless properly introduced, telling them in retrospect "Oh, that spell you just cast? It also kills puppies" without any prior way of knowing is a recipe for frustrated players feeling that you're shifting the rug under their feet, and that's just plain Not Fun.

What you can do to mitigate that is to introduce this spell in such a way that its powers aren't clear and well defined, which can allow adding a side effect that isn't obvious. Don't just give the players a scroll with the spell, make a point of how mysterious and different it is. Have them find the scroll deep in a dungeon, written in an unfamiliar script, and after the wizard spends some time decyphering it, tell him he's reasonably certain of the spell's effects.

Of course, the pitfall here is to avoid making it too obvious that there's a catch to the spell. One way to avoid that is to have other spells - even most spells - be surrounded by this fog of confusion. Consider, for instance, the computer game nethack, where potions and scrolls are anonymous when first encountered, and you have to experiment to see what they do - in this case, you don't feel cheated if a scroll does more than you expected, because it wasn't too explicit in the first place.


A good place to look for example is books that detail unusual or powerful magic items, like AD&D 2e's Book of Artifacts. These are magic items that are described, a-priori as not obeying the standard rules. See this quote from p.6:

Guideline #1

Artifacts are about wonder [..] so they have to be surprising, awe-inspiring, and unpredictable [..] Artifacts can't be ho-hum devices bound by the standard rules of magical devices — the dreary realities of charges, command words, and the like. Artifacts exist to break the rules.

A good analog for you here is the Book With No End (p.25), which is a spellbook with random spells inscribed on each page, and whose effects you can invoke - but at a cost. Since this isn't a normal spell-scroll or wand, but a book that is explicitly marked as different ("covers bound in the hide of a hatchling red dragon and hinged in gold. A golden clasp seals the volume and illuminated sigils emblazon the front and back."), the players will expect differences. And you can spring them immediately, or at your leisure.

  • \$\begingroup\$ I agree that a magic item can be used without having full comprehension of its function; There's a lot of established adventures and such built around this. I was asking about spells, though. Do you have any examples of spells not being fully understood by their casters? \$\endgroup\$
    – GMJoe
    Feb 24, 2015 at 0:12
  • \$\begingroup\$ As I said, no, there isn't any published precedent for it that I know of, but it shouldn't matter much. \$\endgroup\$
    – lisardggY
    Feb 24, 2015 at 5:03

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .