Is there a rule for how to handle creative use of spells?

Question

During a fight in a semi-flooded room, one of my players wanted to use Shocking Grasp on the water:

Lightning springs from your hand to deliver a shock to a creature you try to touch. Make a melee spell attack...On a hit, the target takes 1d8 lightning damage, and it can’t take reactions until the start of its next turn.

Wanting to reward him for a creative use of the spell, I allowed it, using an attack roll of AC 10 and hitting all creatures within 10ft of the spot (including caster).

Is there any rule for these situations? I want to reward creativity without unbalancing spells that are meant for single-target use.

Answer 1

Specific

The first question you need to ask is if the creative use of the spell agrees with the spell requirements.

PHB, p. 275:

Lightning springs from your hand to deliver a shock to a creature you try to touch

This spell requires you to deliver on a creature, and not an object.

Now, this doesn't really answer your general question about creative use of spells, but it does give guidance on the specific example you gave.

General

Generally, The Rule of Cool* should encourage creative solutions, as long as they fall within agreement of the rules. Ultimately, there is no real guidance as to how to handle this as DM other than 5e giving the DM ability to adjudicate decisions. You've got the freedom, you've got the power, just come up with something reasonable that is fun for everyone.

Also consider other effects someone's creative idea may have. They may want it to work one way, but if you see additional effects that could happen, then feel free to add them.

In the case of something like Shocking Grasp, instead of targeting the water (which is not a valid target), the player could target a creature who is in water and have the electrocution spread out out from your target to effect anything in the water (foes, friends, and possibly/probably self.)

* Rule of Cool, Matt Mercer

It is a trope that essentially means a willing suspension of disbelief for the sake of a cool moment... In RPGs, this generally refers to occasionally allowing the chance for ridiculous stunts or unique interpretations of the some of the rules or features of a system for a possibly cool moment.

1. In an RPG, the Rule of Cool means giving your players the chance to perform ridiculous stunts or bend the rules a little bit in the sake of an awesome scene.
2. Be warned, you should establish the level of craziness your game will allow early on to play with people’s expectations.
3. Apply the Rule of Cool sparingly—that goes for the GM just as much as the players! Too much gonzo action will turn your A Song of Ice and Fire RPG into a Dragon Ball Z game faster than you can say “Super Saiyan.”
4. Gauge which player actions are viable, and which are abuse. This is more art than science, but you should reward creativity while dissuading players from reaching too far too often.
5. And don’t forget: most RPGs are designed to tell stories of epic fantasy! Never say never—there’s always the chance someone rolls a natural 20!

Answer 2

It is a tricky question to answer as it falls into the the "RAW, spells can only do what they say they can do in their description, but also RAW you are the DM, you can do what you like" answer, which as it stands would go in the non-answer bin.

However what you are asking appears to be "I want to allow my players to use spells in ways that are not RAW (for instance allowing single target spells to target multiple creatures in specific situations) without unbalancing/breaking the game. Is there any rule or guidance to help me?"

Simple answer as to rules, as already stated is no, not beyond the almost trivial "you are the DM and can do what you like".

DMG p.4

The D&D rules help you and the other players have a good time, but the rules aren't in charge. You're the DM, and you are in charge of the game.

And as a referee, the DM interprets the rules and decides when to abide by them and when to change them.

However I have some advice which, despite being opinion based and not RAW either, does come from real experience which hopefully takes this answer out of the bin addresses "when to abide by them and when to change them" and makes it worth reading.

When allowing spells and abilities to be used in a way not covered by the rules there are some principles/strategies I try and follow:

• Creativity is good and fun and that is the the point of the game - to have fun. Players, and DMs, like pushing the limits of spells and abilities, using them in new ways and making them potentially epic parts of a good story. Something to be encouraged and used, but within limits.
• If something happens once, the players will expect it to happen that way next time too. Always. And they will take advantage of it in new iterations of the creative use of the spell. Always. For instance the party cleric starts to prepare create water spells and the party plan to flood every combat before dropping in shocking grasps or lightning bolts. You have a situation where every credible defensive structure now has a to have a big drain designed in to defend against this spell combo, as it would be known to anyone with Arcana skill and a decent int. Alternatively you are set up for a heated discussion with a player about why they can't do it "this time". And either your game potentially gets a bit broken.
• Bear in mind that 5e is a Rules As Written game and you have to respect the time that has been taken to design a balanced set of rules that does very well in keeping things fair, at avoiding "arms races" between the DM's control, their ability to present a challenge and create the story, and the player characters' abilities.
• If it is a good, fun idea and does not look like it will break your game then discuss it with the players, make it a house rule if you can agree on it, with the caveat that it can be rescinded in the future if it does not work out.
• Magic does not follow the laws of physics, it ignores them, that's why it is magic. This is more important than you might think and it's a good idea in my experience to be wary of justifying effects in terms of anything but the most basic application of our modern understanding of science and technology. I've a masters degree in physics and am a science teacher and if I applied even the little I know about optics, electricity, chemistry and all the rest, the rules and the fun would grind to a halt pretty quickly. For instance a discussion that might arise from your example might be whether a create water spell creates water with the impurities required to provide the ions that are responsible for the movement of charge (pure water is a pretty good insulator) and whether the targets are sufficiently grounded to create a circuit. This would rather detract from the game, for me anyway. You know best where to draw this line in your game.

Considering these ideas makes allowing spell use in the way you describe either very rare or only as one offs in the games I run. The players go along with that with the understanding that no one wants to break the game but everyone wants to have fun.

Answer 3

No, there is no direct rule on how to reward creative uses of spells. This is the point where you must make a choice as a DM, as no specific set of rules exist for every scenario you may encounter. It is your responsibility to either:

1. set limits to keep creativity from becoming exploitation,
2. follow the guidelines to the letter, or
3. if your players do not seem to want to exploit GM rulings, cautiously rule on a case-by-case basis.

Your choice is really up to you, and how you want your players to think.

Answer 4

D&D5 has the advantage/disadvantage mechanic which can be used to quickly handle minor flights of creativity. If a player can make a good point to why the environment or the specific situation aids his spell, he gets an advantage on his roll. If you make a case for the enemy being less vulnerable to an attack, the player gets a disadvantage to his roll. It works the other way around if the target has to make a save against the spell.

For the more creative applications of magic I refer to other answers: Rule of Cool and Never Mix Magic and Physics.

Answer 5

I would be extremely wary of modifying a spell to give a better result. Think about every change as a new spell that you are giving away for free. But somehow only spellcasters get those benefits to their PC's versatility and thus to their overall power level - never the less-magical PCs. That doesn't seem very fair.

While the Rule of Cool is a real thing, and important, it is even more important to be fair. Most of all, ask yourself this question:

Is it a freak occurrence that is certain not to happen again?

If so, then go for it. Otherwise, expect the PCs to later try to abuse the opened exploit as much as they can.

Now, when the target is not in water, where does the electricity all go? As the spell is cast directly on a target, all the electricity goes inside it. But where does the electricity go afterwards? If it were "real" electricity, it would flow through the target's body and then into the ground. But here it is "magical" electricity. It just doesn't get out at all: it has done its damage, end of story.

In water, trying to apply "common sense" to this magic spell could lead to all kinds of weird results. Why would the electricity remain in the target to fully zap it, when there is so much water around to dissipate it? After all, electricity likes to flow where there is least resistance, right? So "realistic" logic could even say that the damage is actually reduced!

Even if you could target the water itself, instead of only a creature, then the electricity would just spread out and mostly go to the bottom directly. You don't get "extra" electricity; it is the same amount. So at best, if it spreads in a 10-foot radius, you take the damage and spread it between multiple targets - you don't multiply the damage!

You can also flip the situation around to guess that the whole thing is actually way out of whack, as in this example:

Initial situation: PC casts it on a target in water, gets the DM to give extra results for the spell, all nice and smiles all around. So far so good.

Flipped situation: PC casts it on a flying target. DM would have to be fair and this time the spell should do next to nothing, right? After all, if the spell works "way better" because water is such a good conductor, then the spell should work "way worse" because air is such a good insulator, right? But suddenly, this time players whine about unfairness and how their spells should work as written. Or they shut up, but are clearly unhappy.

So, if it is that badly unfair in the flipped situation, then it is also that badly unbalanced in the initial situation, too.

Since there are "realistic" arguments both to make the spell stronger (water is a good conductor!) and also to make it weaker (which can also mean it dissipates the electricity away from the PC better!), I just wouldn't mess with the spell at all.

Previous editions had complex rules about how elemental spells interacted with different environments, and those are all gone from D&D 5e - which is a very strong indication that in general spells should not be "adjudicated on the fly on a whim". Just let the spells do what they do "because magic".

The alternative is constantly risking opening a big can of worms each and every time.

Suddenly, that little single-target spell can damage up to 12 Medium-size targets that are standing in water. You've just given that guy area damage. And getting at least some water on the ground is not all that hard to do, too.

You would not make the fighter's "+1 light-emitting sword" suddenly gain the power to blind every foe around the instant he lights it up "because at night our eyes become extra sensitive against light, right?". Same thing here: avoid giving free unwarranted power boosts to spellcasters.

Sure, the Rule of cool is cool and all that. But 99% of the time you would instead paint yourself into a corner where suddenly that spell works way too strongly, way too often.

Say the PC is swimming in a water tank and suddenly gets entirely surrounded by not 12, but 50+ Small-sized water goblins that each have nice claws and teeth? No problem, cast the 1-target spell that is now a "lightning-fireball" and fry them all (taking a bit of damage, sure, but hey, it's better than getting attacked 26 times every round).

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In short, how I would suggest ruling on this spell, for various reasons:

• Based on RAW: no, the spell does what it states, nothing else.

• Based on general common sense to avoid breaking game balance: also no.

• Based on avoiding lots of future headaches against arguing players who, in the long run, will definitely start trying to exploit that "nice trick" as much as they can: also no.

• It's important that for every on-the-fly ruling you make, you really have to it jot down, because it will be used by the players later on, and they'll expect you to apply the rules consistently. So, based on minimizing in-game overhead and needing to memorize all those house rules and future such headaches: also no.

• But based on Rule of Cool: yes. And it is really the only reason to do so; everything else points to a very strong "No"!

But if you go with "yes", you definitely do not need to go overboard here! The most I would do is give advantage to the attack, just as if the target was wearing armor.

If I made the lightning "spread out", then the damage should also be "spread out". Now this can have very interesting game repercussions later on: when the group meets that blue dragon and they are near a shallow lake, they can remember that electricity attacks spread out in water, and decide to all jump into the lake. Now, instead of completely frying one PC at a time, the damage will be spread out - so they will all be pretty damaged, sure, but will probably win the fight instead of getting killed off one by one.

Basically, any house ruling you make can be used to benefit the players, whether you are boosting the power of a spell (PCs start to try to use it everywhere), or nerfing it (PCs start using that as a defense). But overall, I find that attack boosts tend to break the game more than defense boosts.

Answer 6

The answer depends on what kind of game you are playing.

If you are playing it primarily as a wargame, which is how Jeremy Crawford clearly sees it, then a spell is just "a rule" and can only have the mechanical effect the rule states. No more. No less.

If you are playing it as a narrative game, which is to say with the purpose of creating a story, then the question becomes "what makes narrative sense?" This is a subjective call and why you need a Gamemaster to make it. The game-master should understand in a narrative way the physical laws of their world and then apply that to figuring out what happens.

Narrative play goes way back in the history of roleplay games, as also does wargaming. As early as the first edition of Champions there are specific sections of the rulebook that talk about the fact that a 5D6 fireblast is first and foremost a FIRE blast and should have the effect on the environment any intense flame woudl have.

The Crawford POV represents one extreme of this dichotomy. Fate Core and Theatrix represent the opposite extreme. Most games fall somewhere in the middle and ANY game can be played in any style if the GM is willing to put the work in to make the system do it.

Answer 7

Allow it once

There are two levels of creative use for spells

1. Using the spell in a way or combination that is unforeseen or is not covered by the rules, or at least it is not clear cut and requires adjudication to resolve. An example could be combining Resilient Sphere and Protective Bond. There you can make a ruling and then apply it going forward.

2. Using the spell in a way that does not work under printed rules. For example, many tables choose to change the targeting rules for some cantrips. This is the case you describe. The spell targets a creature, so you only can cast it on a creature. Not on water. There are no rules for how to not follow the rules, other than the fundamental rule that the DM can overrule the rules.

Changing the rules

The rules are set up for balance by the game's designers, based on long experience. They aim to keep all classes viable. They aim to make challenges not too easy or too hard. They provide training wheels or a safety blanket for the DM.

Nothing is perfect of course. And if you have good reasons, or want another play experience, you can change them. It's just that by doing that, you are getting into game design territory, and that is inherently more dangerous. You are breaking a rule that may be there for good reasons. A small minority of DMs have as much experience in designing game systems as the game's designers. It is easy to make a change that looks reasonable, but that has unforeseen consequences.

In the end, anything you do in your home game is all up to you and your friends' idea of what is fun. (Only when you want to play with other players at conventions, in organized play and at tournaments, you need to assume that other participants will expect you follow the printed rules. Tournaments historically led to the a codification of rules in AD&D).

One time exemptions

Most of the other answers are warning against allowing creative, off-label, against-the-rules use of a spell, even if it is cool and will create an awesome experience or encounter, because players being what they are, will then use that tactic again and again. Throw the backpack over the lich's head to block all their spellcasting? Create water and shocking grasp to electrocute batches of foes? It's cool the first time, but it gets old fast.

I have an approach that has worked well for me in handling this: Allow it one time. in the situation the players came up with a cool idea and get out of a fix. So what you can do is say: OK, I'll allow this now, but you must understand this is a one-time exception, normally under the rules this would not work. Next time it won't. In my experience, they will be delighted to take that offer, you all will have the super cool fight, and there will be no follow-on damage of repeated use. They'll have to come up with another idea next time.

This approach is not consistent, and many people dislike this, as they want consistency in their world. As a trade for consistency, you get another kind of safety blanket: if you only allow potentially unbalanced exploits one time, they will not have a detrimental effect on your ongoing campaign, and will not add up over time either.

It also helps flow of play, as you do not need to investigate all the possible implications to avoid what you rule will create problems later, so you can make fast decisions and keep the action and engagement going.