Casting an invalid spell

[BurgerBeast]

For anyone who hasn't noticed, there's a thread about what happens when hold person is cast on someone who is under the effect of mirror image.

As part of the thinking I've been doing, I've been wondering about what happens when a player declares that his PC is casting a spell in an invalid way. I'm not going to argue against anyone. I'm just curious to see what people think.

I am operating on the assumption that there is no RAW on this. If anyone does notice that there is RAW on this, please point it out.

For the purposes of this exercise, please ignore metamagic effects.

With regard to each question:

A. can the player insist on trying (or does the DM just say "invalid" and require the character to do something different)?
B. What happens?
C. Does it burn resources? (i.e. spell slots, actions, material components)

What happens if a player tries to cast a spell:

1. in less than the required time (for example a spell with a casting time of one action using a bonus action instead)?

2. at a target that is out of range?

3. without using verbal/somatic/material components? (answer separately if the answers are different)

4. for longer duration than the given duration?

5. at an invalid target (i.e. a creature instead of an object)?

6. in a different area the than it has (i.e. a cone instead of a cube)?

1. A. He can. B. The spell fails. C. He loses an action (of the type he tried to use), a spell slot, and any material components.

2. A. He can. B. The spell fails. C. He loses an action (of the type required of the spell), a spell slot, and any material components.

3. A. He can. B. The spell fails. C. He loses an action (of the type required of the spell), a spell slot, and any material components.

4. A. He can. B. The spell lasts for the normal duration. C. He loses an action (of the type required of the spell), a spell slot, and any material components.

5. A. He can. B. The spell fails. C. He loses an action (of the type required of the spell), a spell slot, and any material components.

6. A. He can. B. The spell is cast using its normal area type at the most sensible location and orientation. C. He loses an action (of the type required of the spell), a spell slot, and any material components.

[PhoenixPhyre]

For anyone who hasn't noticed, there's a thread about what happens when hold person is cast on someone who is under the effect of mirror image.

As part of the thinking I've been doing, I've been wondering about what happens when a player declares that his PC is casting a spell in an invalid way. I'm not going to argue against anyone. I'm just curious to see what people think.


Just FYI: I had a thread on this exact topic (ok, a little more general) about a week or two ago http://www.giantitp.com/forums/showthread.php?498790-Adjudicating-Invalid-Actions. To sum up, the consensus was that invalid actions that the character would know were invalid should be pointed out before wasting an action or a resource. If the character wouldn't or couldn't know they were invalid, let them consume the resource and learn information from it.


To answer the questions (resources include actions, slots, and consumable components):

Impossible, player must choose a legal action.
Warn about range--if the player insists, the spell fails and wastes resources.
Impossible, player must choose a legal action.
Spell fails at end of listed duration.
If the character should know that the target is invalid (ie no illusions, disguise, concealment, etc), warn. If they insist, spell fails and wastes resources. If the character couldn't know (illusions, disguises, etc), spell fails, wastes resources, and the character can make the appropriate check (or, depending on the cause, learns outright the reason for the failure).
Impossible, the player must choose a legal shape.


My general operating principle is that the characters aren't stupid. They know the limits of their spells and won't spend resources on invalid actions unless there's an overriding reason (indicated by the player knowingly insisting on an invalid action). #1, #3, #4, and #6 represent trying to break the bounds of the spells and smacks to me of trying to game the system. If I were feeling very generous, I might allow some kind of check for #6 as long as the total area/volume covered by the two shapes were comparable. That would represent the character bending the spell into a new shape.

[JackPhoenix]

1: A: He can, but it won't help him B: nothing happens C: nope, he didn't cast anything in the first place. At worst, he'll lose an action by gesturing and shouting nonsense

2: A: He can B&C: RAW, he can't, so no resource lost, if I felt mean, depends on spell, spells with attack rolls or AoE's could plausibly fall short if the caster miscalculates the distance to the target, using the resources

3: A: Still the same B: nothing hapens C: nothing cast, nothing lost. At worst, loses an action by doing ****

4: A: You know the drill B: spell works as normal C: spell cast as normal with normal requirements

5: A: Do I have to repeat myself? B&C: depends on spell and target. Some spells can't be cast at all (trying to target a creature with Heat Metal, object vs. creature), other may be cast but fail to take effect (Charm Person on animal, both are living creatures, but of a different type)

6: A: meh B&C: the spell is cast with normal parameters, using the appropriate resources

[Kane0]

What happens if a player tries to cast a spell:

1. No, choose something else to do. Don't mess with the action economy, man. You can try to 'rush' a ritual though, with similar restrictions to below.

5. Usually works in a way that 'makes sense'. For example Eldritch blast targets creatures, but I allow it to work just fine on objects. Using a fireball to wipe away all mirror images won't work though.

2, 3, 4 & 6. Depending on the method used (Arcana check, higher spell slot, magic item, allied help, etc) and magnitude of what you want to do, may work just fine, work with a caveat or fail entirely. Resources (including action cost and spell slot) are consumed in the attempt, and in some cases extra effort may be required (costly spell research, special training, etc)

I'm pretty lenient. I'm the kind of DM that will allow my players to invent new spells and such, so long as it's balanced. I do a little homebrewing so I've got a decent eye for broken mechanics so my group trusts that something fair is worked out. At my table the rules exist to provide the gateway to fun, not block passage to it.
Mind you completely ripping off other abilities (like a sorcerer's metamagic) is not cool, especially if the original owners of said abilities are already present in the party. Those are the default options, what I offer is not intended to replace those nor render them irrelevant. If you want to squeeze an extra 10' out of your magic missile thats fine, if you want to be a firebolt sniper get the feat or some sorcerer levels.

My favorite instance was when trying to invent a new spell to entrap a foe in a whirlwind of force. I did all the required time and resource investment (about a weeks worth of study and a thousand GP or so) to research and develop it and when I did some 'field testing' in our next combat I ended up losing control and the thing turned into a maelstrom over the next few rounds as I kept failing arcana checks. Eventually it burned itself out but it left a permanent spellscar in the area, and I wen't back to the drawing board. I never found a way to keep it fully under control so the checks were required every time I cast it but I was able to apply my knowledge and experience gained to similar spells, extending the range and duration of a couple other force and area spells with similar (though easier) checks and costs attached.

[Slipperychicken]

My Answers:

1. Invalid casting time or components? It fizzles (lose the spell slot and actions). This applies even if the caster wants to use a "longer" casting time. A bonus action spell can never be cast as an action, for example.

2. Out of range? It fizzles (lose the spell slot and actions)

3. Invalid component inputs? It fizzles (lose the spell slot and actions)

4. Duration too long? That's not an option you can change. It expires at the maximum duration.

5. Invalid target? It fizzles (lose the spell slot and actions).

6. Wrong shape? That's not an option you can select. You can't say "my fireball is a cube now". It always casts in the correct shape. If it's something variable like a wall of stone and you choose an invalid shape, then it fizzles and you lose the spell slot and any actions involved.


As a GM, I'd typically warn the player: "Are you sure? At that range, the spell will not work; it will fizzle, and you will lose your action", or "you cannot make the spell last beyond the maximum duration, it will expire at the maximum duration", "That is not a valid shape for a fireball, it can only be cast as a spherical burst. If you cast fireball, it will appear as a burst and not the shape you specified". If they insist on trying anyway, I'll narrate it fizzling or otherwise not working the way they said.

And it's a different thing entirely if a player says something like "I want to use the spell research rules to invent a cube-shaped version of the Fireball spell" or "I want to research a longer-lasting version of sleep". In that case, I'd evaluate whether or not that is reasonable, advise them any caveats like "the spell would be a higher level" or something, and then I'd most likely allow them to attempt to research the spell. This will not put the campaign on hold; they must find the time do it in-universe; the forces of darkness will not stand idly by while the players invent new spells to stop them.

[Pex]

If a player Honest True got a rule wrong, misunderstood a spell in what it does or how it works, forgot some information the character learned but the player was told about it a real world week, 2 weeks, a month ago, it doesn't happen, the player can do something else, no resources of any kind were used. It's just a game.

If there's no way the player/character could possibly know the spell wouldn't work, perhaps even the intent of the encounter, the spell is cast, it doesn't work, and the character/player learns something. It's smarts to have wasted a spell that way, but it's part of the process of learning and the fun of the game.

A DM should realize and accept the reverse-metagame. This is where a character does know something in character but the player hasn't a clue out of character, perhaps not even knowing he should be asking a question about it. Depending on what that something is the DM just tells the player his character automatically knows, perhaps due to being of a particular class or proficiency in a skill or being from a particular geographical area, or the DM can initiate the player to roll a check and provide information based on the roll.

[Sabeta]

snip
1. A. He can. B. The spell fails. C. He loses an action (of the type he tried to use), a spell slot, and any material components.

2. A. He can. B. The spell fails. C. He loses an action (of the type required of the spell), a spell slot, and any material components.

3. A. He can. B. The spell fails. C. He loses an action (of the type required of the spell), a spell slot, and any material components.

4. A. He can. B. The spell lasts for the normal duration. C. He loses an action (of the type required of the spell), a spell slot, and any material components.

5. A. He can. B. The spell fails. C. He loses an action (of the type required of the spell), a spell slot, and any material components.

6. A. He can. B. The spell is cast using its normal area type at the most sensible location and orientation. C. He loses an action (of the type required of the spell), a spell slot, and any material components.

Various works of fiction have presented different variations on Magic, and that may cloud my judgement on the matter. For example, Tales of the Abyss was a fantastic game with a delightlfully well explained magic system. One of my favorite moments in the game was how one character explained why his AoE Magic didn't hurt allies. Turns out Magic in their world was so well structured, that he could magically affix a "friend or foe" marker to them that makes his friends safe from his magic. If D&D's Magical system is as well structured then naturally Targetting is a physical part of the spell, and as such any spell without a viable target simply wouldn't be cast, as the magic wasn't structured in a way to allow for that.

Unfortunately, skimming through the SCAG makes me think that this is not the case. That magic is a very chaotic thing. In that case, I'll instead reference Runescape's Magic system. In Runescape, people cannot cast Magic. Sure, the Elves can do it. The Mahjarrat were quite skilled at it, and obviously the Gods could do whatever they please, but mere Mortals had no such talent. For that, they need Runes (where the game gets its name from). To greatly simplify matters, think of Runes as planar charged rocks that when invoked create Magical effects. If you want Fire Runes for example, you'll have to pay a visit to the realm of Elemental Fire.

But magic is still chaotic. The Runestones are just rocks full of power. They themselves don't contain spells, and just using them by themselves (not doable with gameplay) simply releases the energy. Thankfully the Wizard's guild has gone to great lengths to research Magic in Gielinor, and has even managed to allow the Runestones to lock on to major landmarks for teleportation purposes. What I'm getting at here, is that a creative individual could cast spells in unintended ways (in fact this happens several times.) that are outside of the spellbook.

I personally think that D&D (which Runescape was loosely based on, or more accurately the MUDs that were based on D&D) falls into the latter camp. That Magic is not a strictly regimented thing, and that all of the rules that govern magic have more to do with assisting the mage in invoking the weave properly rather than being mandatory components for the spell.

With that wall of text out of the way, allow me to answer these questions under that assumption.


1. in less than the required time (for example a spell with a casting time of one action using a bonus action instead)?

Because Cast a Spell cannot happen more than once a turn (within standard action economy anyway), the maximum abuse this could recieve is Spell+Cantrip, or rather Spell+Action. I would probably allow the caster to attempt the cast. I'm not going to write out in great detail all of the math I would impose on it, but essentially the first two penalties are A) Damage and/or Duration reduced, and B) Accuracy and/or DCs reduced as well. I would probably also write in to roll a 1d20. Above 10=you can do it, less than 10=you lose the spell and the slot. Nothing happens. Critical Success means no penalty, cast the spell as normal. Critical Fail means the spell is reversed, and you alone suffer its effects. (ie: Attempting to Fireball causes you to take 3d8 Force Damage, but if your entire party is adjacent to you they aren't going to be fried. It's a magical "backfire")


2. at a target that is out of range?

If the spell doesn't technically require a Target. The spell goes off without a hitch. You might not do damage.
If the spell does require a target, and it's out of Range, I would simply consume his reaction. If he doesn't want to use his reaction for some reason, but does want to try and cast the spell then I guess I could allow it. He would cast the spell at the nearest point to the monster it could possibly be without exceeding its range, and if the monster walks through that on its turn it takes the damage or effect. (Turns are technically simultaneous afterall...though that might be a bit OP in terms of zone denial)


3. without using verbal/somatic/material components? (answer separately if the answers are different)

See my response for number 1. However, I generally handwave Verbal anyway. I may impose concentration on the spell if you forgo material components, and the more costly the spell the more likely failure will occur without the proper resources. Likewise, the higher the level of the spell the more important it is that you get it right, and the more likely not reciting your verse or whatever matters, and therefore could lead to a spell fail. Unlike other rulings though, the spell will simply fail. Not be cast with lesser effect.


4. for longer duration than the given duration?

If it wasn't already, it now becomes Concentration. Every additional round you try to hold it requires a Con Saving throw with disadvantage to maintain.


5. at an invalid target (i.e. a creature instead of an object)?

I never understood why Hold Person and Hold Monster were racist. If I had to guess it has something to do with the mystical energy of the weave or whatever being uniquly different between humanoids and monsters. Either way, there are too many cases for this so I'll refrain from commenting.


6. in a different area the than it has (i.e. a cone instead of a cube)

Interesting premise. Evocation Wizards already kind of do this though, so it's not totally unbelievable. As long as the area is less than the original area I would probably allow it, but that's for the more structured spells. IE: Forcecage can be a cube or a sphere I don't really care. Fireball however isn't changing, sorry.

I will warn everyone now that it is highly unlikely that I will change my mind on this, save for points that I admitted to being unsure of.

[Zalabim]

3. Without using Verbal/Somatic/Material components.

The book actually says right in Components, before describing each type in detail, if you can't provide one or more of a spell's components, you are unable to cast the spell. I don't think any other example has quite so definite of a "no, you can't" in the book.