Is grabbing an opponent's arms to prevent casting within the "scope" 5e's combat?

Question

Recently, my players faced off against an enemy spellcaster. During the fight, the barbarian stated that it was his intention to grab the spellcaster in a bearhug, pinning his arms to his sides to prevent him from casting spells with somatic or material components (unable to reach his component pouch).

I'm pretty sure that this doesn't fall under the grapple rules, because grapple has no rules other than preventing movement. Normally when something is outside the rules, I would fall back on the standard adjudication cycle:

1. The DM describes the environment
2. The players describe what they want
3. The DM narrates the result of the character's actions

However, this got me thinking about the "scope" of 5e combat. Certain actions, such as Called Shots are outside the scope of 5e combat; that is to say, they try to go beyond the inherently abstract nature of AC, HP and attack rolls to simulate aiming at specific body parts, which the game was not designed to do. Thus, it seems the correct decision when a player wants to "shoot him right in the eye with my arrow" is to simply say "the system doesn't support that" rather than rely on the standard adjudication cycle.

Like a Called Shot, this arm-pinning ignores the abstract nature of combat by targeting a specific part of the body, shutting down an opponent without reducing their HP. This becomes more blatant if we imagine the barbarian had said "I want to break his arms so he can't cast spells." Furthermore, one could imagine an analogous case in which the same maneuver is used to prevent a melee combatant from using their weapons.

On the other hand, creative play should be rewarded, and "doing anything you can think of" is one of the main draws of D&D over, for example, video games. If the scope of combat is constrained too tightly, combat devolves into "pressing the attack button" over and over.

My question: which case should my player's desired action fall under? Is trying to pin an opponent's arms within the scope of 5e combat? Should it be adjudicated via a contest of some sort, or by saying "the system doesn't support that"?

Answer 1

It's not in the rules, but DMs have the latitude to allow it.

As you point out, I couldn't find anywhere in the rules to support an action like that. However, the system allows for DMs to make judgments about whether an action is reasonable/possible, as well as how difficult it is (PHB 192):

When you describe an action not detailed elsewhere in the rules, the DM tells you whether that action is possible and what kind of roll you need to make, if any, to determine success or failure.

This specific instance is probably balanced.

Thus, it's up to you as the DM to determine whether this specific case should be allowed. More specifically, we need to ask, "If creatures are allowed to do this, would they always do it?"

From a theorycrafting perspective, it seems roughly balanced. The effects of pinning a caster's arms (or any character's arms, really), is roughly comparable to Hold Person, which is a second-level spell. We can take a cue from Hold Person, and say that if we want the effect to last multiple rounds, the grabbed character should get an opportunity to escape every round (as if from a grapple). The rest of the balance is probably a wash, because such a pin prevents the attacker from doing anything else, but they can do it for free.

We can also look to the grappler feat, which does something similar (PHB 167):

You can use your action to try to pin a creature grappled by you. To do so, make another grapple check. If you succeed, you and the creature are both restrained until the grapple ends.

Consider that you're allowing any character to take the benefit of this feat for free, and that the effect you're trying to create is actually more powerful than this feat. I'm personally OK with this, given that my players don't really use feats, but it's ultimately up to you and your players.

I have used a similar rule in actual play, and it seems to be a bit underpowered compared to other possible actions. I had a few of my NPC characters try to grab and pin the PCs, both to prevent them from escaping and to incapacitate them. I required my NPCs to initiate a grapple with one action, and then make a contested strength check to pin them with another action. Because the process costs two actions, allows for two "saving throws", does no damage, and still permits verbal-only spellcasting, its opportunity cost is very high--imagine the damage that a strong creature could do in two rounds! Additionally, once they are pinned, the grappler cannot do anything else, which effectively takes them out of the combat. While such an action was appropriate for the situation, I cannot imagine a smart combatant wanting to do this with any frequency.

However, if you do include this rule, you should remember that it will affect your future combats. It might not make much sense to try this move if there are lots of enemies, but it can completely shut down a combat with a solo spellcaster, if they ever move within melee range. It will also open up this option to enemies restraining the PCs, which they might not be super happy about.

Answer 2

Using Opposed Ability Checks / Contests

Let's examine two cases of trying to do this: one with the Grappler Feat and one without.

With the Grappler Feat

If the Barbarian has the Grappler Feat, the grapple does more than simply reduce speed to zero. It allows a chance to restrain the caster with a subsequent action. The pinned/restrained condition does not explicitly say that it prevents spell casting ... but let's work with what we have.

Grapple:

... a Strength (Athletics) check contested by the target’s Strength (Athletics) or Dexterity (Acrobatics) check (the target chooses the ability to use). If you succeed, you subject the target to the grappled condition

The significant grappled condition is: A grappled creature’s speed becomes 0, and it can’t benefit from any bonus to its speed. As you note, that by itself is no prevention to spell casting (unless a spell requires a movement component).

Escaping a Grapple

A grappled creature can use its action to escape. To do so, it must succeed on a Strength (Athletics) or Dexterity (Acrobatics) check contested by your Strength (Athletics) check.

Each turn of grapple is a contest: grappled creature can to get free, which might include casting a spell to do so.

Action Economy Note: this attempt to escape may preclude using an action to cast a spell, but any bonus action or reaction spell casting is still available should the caster try to escape using an action.

Using a subsequent action ... with the feat

• You can use your action to try to pin a creature grappled by you. To do so, make another grapple check. If you succeed, you and the creature are both restrained until the grapple ends.

Restrained Condition from Appendix A: (You both are restrained)

• A restrained creature’s speed becomes 0, and it can’t benefit from any bonus to its speed.
• Attack rolls against the creature have advantage, and the creature’s attack rolls have disadvantage.
• The creature has disadvantage on Dexterity saving throws.

No disadvantage on attempt to get out of the grapple. On subsequent rounds you can use non-weapon attacks (advantage for attacks against caster are canceled out by disadvantage for attacks on the caster).
Note: If your party cleric wants to cast Sacred Flame at this caster, the target has disadvantage on the Dex save ... it's a single target cantrip. But that's not what you are trying to accomplish.

Even with the feat, the DM has to make a ruling.

Recommended Ruling: require an additional contested check to stop the caster from trying to cast during each turn. The caster is resisting with a will. (And likely trying to break the grapple). There is no easy button, the enemy fights back.

Note: Spells with only a verbal component are not going to be stopped. For example, a Command to "grovel" that the Barbarian fails his save on should break the grapple.

Without the Grappler Feat

Reduce the target to speed zero, no explicit constraints otherwise, and of course each turn the caster can try to break grapple. So far, this kind of detailed restraint, while familiar in a cinematic sense from TV and movies, doesn't have explicit rules support with a simple Grapple. Since the Barbarian has not paid the price for the feat, simple grapple should be less effective than grapple with feat.

Rulings over Rules

I recommend that if you want to add this feature or capability, and there's no feat, the Barbarian has to attempt a second Grapple after a successful grapple, each turn/round, with *disadvantage. (Otherwise, why the Grappler feat?). Likewise, the caster isn't restrained. I'd also rule that the Barbarian can make no other attacks when trying this advanced grapple without the feat.

Disadvantage reflects how much harder it is to control a resistant opponent, but leaves open a chance for some heroics or unique happenings during the game.

Inspiration, Advantage and Disadvantage

Does the Barbarian have an inspiration point, previously awarded? The DMG pages 240-241 introduces the use of inspiration:

Awarding Inspiration is an effective way to encourage roleplaying and risk taking ... the character can have no more than one Inspiration at a time.

The lesser case of a bardic inspiration point helping a given roll isn't as powerful as DM awarded inspiration, which gives advantage, but it can't hurt to add a few points to the die roll.

You usually gain advantage or disadvantage through the use of special abilities, actions, or spells. Inspiration can also give a character advantage. The GM can also decide that circumstances influence a roll in one direction or the other and grant advantage or impose disadvantage as a result.

This is the kind of scenario where, as a GM, I see the Inspiration rules as providing that "one special time" that the player with an inspiration point burns that one precious point and gets advantage, to cancel disadvantage when trying to pin/restrain the caster. It is not guaranteed to work, but it can tip the odds in the Barbarian's favor for that first round.

If circumstances cause a roll to have both advantage and disadvantage, you are considered to have neither of them, and you roll one d20.

If the player has not earned an inspiration point, it's less likely that the cool thing he's trying to do will work. If he's earned that inspiration point, there's a better chance he pulls it off.

Inspiration aside, and depending upon circumstances, you can always apply advantage or disadvantage for a given attempt if a circumstance suggests to you that it makes sense. (For either the barbarian, or for the spell caster trying not to be controlled like this). That's one of those judgment things that you'll rule on in each situation as it arises.

No "Easy Button"

Don't forget: every turn, the caster gets that chance to escape the grapple.

Answer 3

Conditions

Conditions aren't generally super easy to come by in 5e - especially those that can completely shut down a character.

If the barbarian is wanting to prevent the spellcaster from casting a spell at all, then from a 5e perspective that is removing their action (or ending their ability to have somatic, material and verbal components.) Given that pinning arms is not a way to stop a verbal component, the only real way to stop a spellcasting action is to stop an action. There is a condition specifically for this: Incapacitated.

An incapacitated creature can’t take actions or reactions.

Restrained is another potential option, but they are still able to take actions.

• A restrained creature’s speed becomes 0, and it can’t benefit from any bonus to its speed.

• Attack rolls against the creature have advantage, and the creature’s attack rolls have disadvantage.

• The creature has disadvantage on Dexterity saving throws.

Changing Restrained to include removal of use of their arms to limit their somatic/material access is less impactful, but still should be considered for it's impact on the game world.

Arms vs. Hands

One other thing to consider is that you are pinning their arms...not their fingers. Nowhere does it say that there is a need for arm movements vs finger movements for somatic components. In fact, all it says is you need a hand free. Not an arm. Pinning an arm to prevent Somatic may not be a viable option.

If you make a ruling that pinned arms equal no somatic movement, then Verbal only spells can always be cast and possibly material if there is a focus (depending on the focus and ruling.)

Lots of spells are still available

Some Verbal-only spells that could have an impact are: misty step (bonus action and remove yourself from the grapple), dimension door (action to completely remove themselves up to 500' away!), immolation, Otto's irresistible dance, the power word spells, sword burst, time stop and wish.

Many of these can do immense damage or completely escape this situation.

Grappling: it just doesn't do it.

Grappling itself does not really provide what you're looking for. Even if your Barbarian invested in the Grappler feat, they'd only generate the Restrained condition (PHB, 167), which would still allow the target to cast any spell.

Rule of Cool vs. Balanced

What your Barbarian wants to do is Cool. But is it Balanced? There aren't many things out there that can make someone Incapacitated. Allowing a Str/Dex-based character to use their Grapple skill on a character that isn't proficient in those skills to effectively remove them from combat is potentially unbalancing. One way of talking to your table about it is by turning the question around.

You are also effectively turning either Hold Person (2nd level)/Hold Monster (5th level) - which are spells that have a spell slot cost, and if the creature saves, result in nothing - into an Attack action (which Barbarians get more than one of) at no other cost then their action. That's incredibly powerful.

Turnaround is fair play?

If this becomes a viable tactic for your players...they should fully expect it to be a viable tactic against them. While they may not always fight spellcasters, there is (if there is one now) always a spellcaster in your party. Do they want this to happen to them regularly?

Still want to do it?

There may still be a way to balance it! Think about what it would take to make it more worthwhile. Possibly it takes multiple Grapple attempts in order for this to work - with a save at the start of each round instead of the end. First attack is the standard Grapple. Next Grapple contest would be to give the Incapacitated condition. Then allow a "save" at the start of each turn for Grappled character, and maybe also require a new grapple check by the Grappler as one of the attack actions during their turn (sort of emulating a concentration type mechanic... or simply give the Grappler the Restrained condition that the Grappler feat gives when Restraining a creature with a grapple.)

Answer 4

Although the scope of this question was in regards to grabbing someone's arms in combat, it's worthwhile to note that grabbing someone's arms wouldn't necessarily prevent casting.

While there are some spells that explicitly state the somatic component required, many others do not.

For example, fireball states:

A bright streak flashes from your pointing finger to a point you choose within range and then blossoms with a low roar into an explosion of flame. Each creature in a 20-foot-radius sphere centered on that point must make a Dexterity saving throw. A target takes 8d6 fire damage on a failed save, or half as much damage on a successful one.

The fire spreads around corners. It ignites flammable objects in the area that aren’t being worn or carried.

But flaming sphere does not state any specific somatic component required:

A 5-foot-diameter sphere of fire appears in an unoccupied space of your choice within range and lasts for the duration. Any creature that ends its turn within 5 feet of the sphere must make a Dexterity saving throw. The creature takes 2d6 fire damage on a failed save, or half as much damage on a successful one.

In cases where there is no specific description, the SRD describes a somatic component as follows:

Spellcasting gestures might include a forceful gesticulation or an intricate set of gestures. If a spell requires a somatic component, the caster must have free use of at least one hand to perform these gestures.

Depending on how you restrain them, they could have "free use of at least one hand" in order to cast spells that do not dictate what the somatic component is. The usage of the spell would be largely up to DM discretion and what they consider "free use." This could lead to rather interesting circumstances should an NPC rather cast fireball at their feet than be captured.

Note to mods: This might be better suited for a comment, but I was unable to fit it within the character limit.

Answer 5

Would be within the scope. Depending on how the PC does it, the nitty-gritty would be up to the DM. However it should just be treated as a PC attempts to grapple the arms of an enemy. This would just constitute an Athletics check, as usual with grappling. However with the condition that the PC doing the grappling would not be able to make an attack action on the target as they are attempting to restrain the targets hands/making them unable to cast spells requiring some form of semantic on their part.