Can I cast a cantrip if I'm holding a weapon?

[stewstew5]

I can't seem to find it in the phb. Can a spellcaster or natural caster (yuan-ti pureblood, etc.) cast a cantrip while holding a weapon in their hands (proficiency varying)?

[NecessaryWeevil]

Wouldn't that depend on its material or somatic components? Not sure why its level would be relevant.

[Sindal]

I can't seem to find it in the phb. Can a spellcaster or natural caster (yuan-ti pureblood, etc.) cast a cantrip while holding a weapon in their hands (proficiency varying)?

The level of the spell doesn't matter
If they don't have a shield or something else in their other hand for any material or somatic components, then yes you can

[Foxhound438]

the only thing that might prevent you from doing so would be somatic or material components, which can be fulfilled by your other hand, provided that hand isn't preoccupied in a shield or grapple or something else.

[stewstew5]

alright neat

[No brains]

I believe the monster manual or XGtE says innate spellcasting doesn't have any components, so if you can cast something innately, like a pureblood with poison spray, you ought to be able to do it with your hands full.

[Tanarii]

I believe the monster manual or XGtE says innate spellcasting doesn't have any components, so if you can cast something innately, like a pureblood with poison spray, you ought to be able to do it with your hands full.
MM definitely doesn't say this, and I can't find it in XtGE either.

Edit: you're probably thinking of:
PSIONICS
A monster that casts spells using only the power of its mind has the psionics tag added to its Spellcasting or Innate Spellcasting special trait. This tag carries no special rules of its own, b'ut other parts of the game might refer to it. A monster that has this tag typically doesn't require any components to cast its spells.

[Misterwhisper]

I can't seem to find it in the phb. Can a spellcaster or natural caster (yuan-ti pureblood, etc.) cast a cantrip while holding a weapon in their hands (proficiency varying)?

Sure as long as you can do one of these:

Use a two hander and a spell pouch
Be a cleric or paladin with a shield
Hold a focus in the other hand
Your weapon could be your focus with certain classes or subclasses.
Since some can use a gemstone as a focus some gems would let you wear it as a ring.

If you meet none of those, you can take warcaster.

[Tanarii]

Hold a focus in the other hand
Generally it's better to keep the hand free with the focus on your belt. That way you can access it (no action required per M component rules) for S/M spells, but leave it alone for S but not M spells.

Especially important for Cantrips, since so few of them are M spells, a focus in hand just gets in the way by occupying your free hand.

[Pex]

War Caster feat lets you ignore the technicality of having your hands occupied to cast spells. It's often overlooked when people discuss the feat. They mostly promote the advantage to concentration checks ability with some talk in being able to cast a spell for your opportunity attack.

[No brains]

I read the third paragraph of Perceiving a Spellcaster at Work on page 85 of XGtE. That's where it claims innate spells have no (visible?) component. It's an odd place to tuck away that rule... or maybe a bad way of phrasing it.

It is more likely that they meant that Innate Spellcasting often, but not always, allows a creature to skip one or more components. The trait varies from creature to creature. It doesn't even have to be innate, like a Flameskull's (non-innate) Spellcasting that lets it skip material and somatic components. I guess you could still identify a Flameskull screaming out a Fireball.

I suppose that in the specific case of a Yuan Ti Pureblood, they do need a somatic component to cast Poison Spray, and thus can't do it with their hands full.

Sometimes it's good to go over the rules like that.

[Tanarii]

War Caster feat lets you ignore the technicality of having your hands occupied to cast spells.
War caster only helps with V/S or S-only spells. Not spells that require an M component. That's most Cantrips though.

[stewstew5]

So for a non-spellcaster class that gains access to certain cantrips but no other spells how would it work?

[Tanarii]

So for a non-spellcaster class that gains access to certain cantrips but no other spells how would it work?
1) Look up the Cantrips casting components.
2) does it have S, M, or S/M components. (V can be ignored for this discussion.)
3) if S, then your PC needs one hand free, or Warcaster to cast with both hands occupied.
4) if M or S/M, your PC needs one free hand, and either access to the specific component (in a pouch is fine), or a component pouch (i.e. The equipment item).

Note that if your PC uses a two handed weapon (e.g. Greatsword or Longbow) that counts have having a hand free. Since in 5e a character can take a hand off the weapon at any time to free it up.

[Misterwhisper]

1) Look up the Cantrips casting components.
2) does it have S, M, or S/M components. (V can be ignored for this discussion.)
3) if S, then your PC needs one hand free, or Warcaster to cast with both hands occupied.
4) if M or S/M, your PC needs one free hand, and either access to the specific component (in a pouch is fine), or a component pouch (i.e. The equipment item).

Note that if your PC uses a two handed weapon (e.g. Greatsword or Longbow) that counts have having a hand free. Since in 5e a character can take a hand off the weapon at any time to free it up.

Paladins and clerics can do somatic components with an emblazoned shield.

[JackPhoenix]

So for a non-spellcaster class that gains access to certain cantrips but no other spells how would it work?

Unless there's a rule saying otherwise in the source of the cantrip (some racial spells make an exception), you at least one free hand to cast a spell with S component. If the spell also has M component, you can use the same hand for handling M and S component. You know, just like it's written in the rules.

However, you can't replace M component with focus unless you have class ability that specifically allows it: notably, rangers, EK fighters and AT rogues can't use focus instead of proper component.

[Tanarii]

Paladins and clerics can do somatic components with an emblazoned shield.
Paladins and clerics are not non-spell casters that gain access to a certain Cantrips. I'll add the quote to make it clear what I was replying to though. :smallwink:

[HappyDaze]

Paladins and clerics can do somatic components with an emblazoned shield.

Last I heard, this does not work for spells with S but no M. In other words, a Cleric lacking the War Caster feat with spear and shield equipped would be unable to cast Sacred Flame without dropping one of the items.

[Misterwhisper]

Last I heard, this does not work for spells with S but no M. In other words, a Cleric lacking the War Caster feat with spear and shield equipped would be unable to cast Sacred Flame without dropping one of the items.

The holy symbol on the shield is their casting focus and they can move it around to do somatic movements with it.

I have never seen the point in taking warcaster on a cleric or a paladin unless you are really worried about concentration.

[JackPhoenix]

The holy symbol on the shield is their casting focus and they can move it around to do somatic movements with it.

I have never seen the point in taking warcaster on a cleric or a paladin unless you are really worried about concentration.

That only works for SM spells. S-only spells require free hand. Hand with material component (or a shield) is not free.

[Misterwhisper]

That only works for SM spells. S-only spells require free hand. Hand with material component (or a shield) is not free.

You can preform the somatic component of a spell with a focus in your hand, you do them with the focus.

http://media.wizards.com/2016/downloads/DND/SA-Compendium.pdf

The even use a specific example of a cleric using a shield as the focus.

[HappyDaze]

You can preform the somatic component of a spell with a focus in your hand, you do them with the focus.

http://media.wizards.com/2016/downloads/DND/SA-Compendium.pdf

The even use a specific example of a cleric using a shield as the focus.

Did you read the full example?

Another example: a cleric’s holy symbol is emblazoned
on her shield. She likes to wade into melee combat with a
mace in one hand and a shield in the other. She uses the
holy symbol as her spellcasting focus, so she needs to have
the shield in hand when she casts a cleric spell that has a
material component. If the spell, such as aid, also has a so
-matic component, she can perform that component with the
shield hand and keep holding the mace in the other.
If the same cleric casts cure wounds, she needs to put the
mace or the shield away, because that spell doesn’t have a
material component but does have a somatic component.
She’s going to need a free hand to make the spell’s ges
-tures. If she had the War Caster feat, she could ignore this
restriction.

That second paragraph should clear it all up.

[Misterwhisper]

Did you read the full example?

Another example: a cleric’s holy symbol is emblazoned
on her shield. She likes to wade into melee combat with a
mace in one hand and a shield in the other. She uses the
holy symbol as her spellcasting focus, so she needs to have
the shield in hand when she casts a cleric spell that has a
material component. If the spell, such as aid, also has a so
-matic component, she can perform that component with the
shield hand and keep holding the mace in the other.
If the same cleric casts cure wounds, she needs to put the
mace or the shield away, because that spell doesn’t have a
material component but does have a somatic component.
She’s going to need a free hand to make the spell’s ges
-tures. If she had the War Caster feat, she could ignore this
restriction.

That second paragraph should clear it all up.

I guess I was wrong.

That makes no sense but those are the rules I guess.

[Tanarii]

That makes no sense but those are the rules I guess.Yeah that's what I was saying earlier about not being able to cast a S (but not M) component spell if your focus is already in your hand. Practically speaking, that only affects characters who have a Holy-symbol emblazoned shield, or are carrying a staff as a focus and weapon.

Everyone else can keep a hand free for S component spell, and access their focus when they need it. Either on a belt loop/holster (wands and rods), or in a pouch, or on a neck chain for a crystal or holy symbol. It doesn't take an object interaction to do that, it's part of casting the spell, per the M component rules.

But yeah, it's probably unnecessarily complicated. Especially for 5e.

(Edit: I'm assuming a staff is so big you must carry it in a hand. As opposed to on a belt loop. YMMV.)

[Dark Schneider]

Cantrips use the same casting rules than spells, look at the components involved, and your feats. They only are the exception when casting a spell as bonus action, you can only cast a cantrip with your action, but not a spell.

About S and M components, the rules say you can use the same hand for both. But do not try "cheap" solutions to wear a shield and focus, you need direct contact with your focus. If not it would be too easy to bypass the requirement, and the rules would say something about it. RAW say you need "a free hand", that's all, and wearing a shield is not "free". That could involve you need to hold the focus, and manipulate in some way, D&D is not so specific, but what is clear is that you need a free hand, that is explicitly mentioned. So what we know is that you need a free hand for manipulating the focus, instead beign embedded in another item.

[kamap]

Some weapons could be handed to your hand holding a shield so you have a free hand and can then retake your weapon when needed. Depends on your DM how he or she lets that work.

[Dark Schneider]

Some weapons could be handed to your hand holding a shield so you have a free hand and can then retake your weapon when needed. Depends on your DM how he or she lets that work.
That's true, you only need to hold the item, but in that case you can't use it that round. So if you attack with your weapon, you don't have that hand free. It is the same with 2-handed weapons, you can hold it with only 1, but not using it.
Notice in that case is the very same than using your free action to draw/undraw the weapon for that hand.

[Arkhios]

Cantrips are just as much spells as 1st level to 9th level spells are (Cantrips are 0-level spells, as mentioned by the book). They just don't use your spell slots.

Because they are spells, everything that applies to spells, applies to cantrips as well.

[JackPhoenix]

I guess I was wrong.

That makes no sense but those are the rules I guess.

It makes perfect sense. The somatic component of SM spells consist of handling the material component or a focus. The somatic component of S-only spell doesn't.

Imagine typing something on a cell phone's keyboard. You can easily hold the phone and type with your thumb. That's SM spell.
Now imagine you have to instead type something on a normal keyboard. That's S spell. Try to do the same while holding a cell phone in the same hand... it's not impossible, but the cell phone (M component) gets in the way, you can't use all fingers, and you're much slower.

[HappyDaze]

It makes perfect sense. The somatic component of SM spells consist of handling the material component or a focus. The somatic component of S-only spell doesn't.

Imagine typing something on a cell phone's keyboard. You can easily hold the phone and type with your thumb. That's SM spell.
Now imagine you have to instead type something on a normal keyboard. That's S spell. Try to do the same while holding a cell phone in the same hand... it's not impossible, but the cell phone (M component) gets in the way, you can't use all fingers, and you're much slower.

A better equivalence for casting the "S without M" spell would be to use that hand for sign language while it's holding the cell phone.

[JackPhoenix]

A better equivalence for casting the "S without M" spell would be to use that hand for sign language while it's holding the cell phone.

Also a possibility, but I can't use sign language, while there's a cell phone and a keyboard lying on the table in front of me

[SleepIncarnate]

Also, I feel like the whole focus thing has distracted a bit with wrong information. The focus doesn't replace S or V components, but does replace M components that a.) don't have a specific cost listed and b.) aren't consumed by the spell. They can help with those rare cantrips that require a material component (such as minor illusion), but they have no effects on a strictly V/S cantrip, such as GFB or BB.

Considering the original question was about how holding a weapon affects it, if there's nothing else in your other hand (a second weapon, a shield, a torch, whatever), then you can cast the spell. If you have something in the other hand and don't have the war caster feat, then you can only cast spells that have only a V component (such as Vicious Mockery).

Hope that helps to answer the OP's question.

EDIT: Forgot to address the issue of two handed weapons and versatile weapons. They fall into a more complicated camp. For most spells, the answer is yes, you can take one hand off tbe weapon to cast. But, some spells specifically require you to make a weapon attack, such as GFB and BB. In the case of those spells, you cannot cast the spell with the two handed weapon if it has a somatic component. You can cast them with a versatile weapon, but you cannot use the higher two hand damage dice for the weapon.

[SleepIncarnate]

Thankfully, GFB and BB are the super rare spells that use V/M but not S, and the M is the weapon itself, so you can still cast those.

[Dark Schneider]

The spells using a weapon as M (the same you use for attack) usually don't have S component, or never, because that. If it had, it is indicating that you would need Warcaster feat to use it with 2-handed weapons, or use it with one-handed weapons and without shield if don't have the feat.
But I can't remember one of those spells with S component.

[HappyDaze]

Thankfully, GFB and BB are the super rare spells that were designed with an understanding of the RAW, so you can still cast those.
Adjusted for how I view it. Too many existing spells suffer from just carrying over assigned components established prior to the hard coding of how the component requirements work.