Does casting a spell negate a long rest? - Rules & Game Mechanics - Dungeons & Dragons Discussion - D&D Beyond Forums (2024)

I had the idea to cast spells like mage armor shortly before a long rest ends, so I can have the defence while haveing a extra spell slot for the day, but I wanted to know if casting a spell would stop a long rest from taking effect.

I just read this:https://www.dndbeyond.com/sources/basic-rules/adventuring#Resting which says "Casting spells" is one of the things that "breaks" the long rest, but does that mean spells as in more then one, or does that mean any spellcasting? Also, does that count cantrips?

Edit: lol, l completely missed the "more then one hour" part. Guess that means my plan works, RAW?

First off, while as a player I admire your munchkinery, as a DM I would tell you to just cast it after the rest.

That said: casting spells does interrupt the long rest, but unless the interruption lasts for more than an hour, the rest can be continued. This means you can rest for 7.5 hours, cast a spell, then rest the remaining half an hour to complete the long rest and get the benefits.

And yes, cantrips are spells.

It should say something to the effect of"If the rest is interrupted by a period of strenuous activity — at least 1 hour of walking, fighting, casting spells, or similar adventuring activity — the characters must begin the rest again to gain any benefit from it."

So,what I can see RAW is that you should be able to spend the spell slots that you currently haveduring the 2 hours of light activity, but you don't regain spell slots until the end of the long rest. If you didn't save up "today's" spell slot, there's nothing to use until the end of the long rest when you get "tomorrow's" spell slots.

The subjective nature of the term "strenuous activity" might require a DM to rule on how that is applied. I might agree that practicing weapons drills, or ritual casting spells could be considered light activity, but I would definitely rule acombat encounter to be strenuous.

They do say "fighting" in there. If that's not combat, what is it? Long verbal arguments? I don't see that as "strenuous activity" really. On the other hand, spending an hour "walking" is apparently strenuous activity, so maybe they really do mean you can only cast one spell, including a cantrip, during that hour.

The way I read it, what they mean by "walking, fighting, casting spells" is that doing them all at the same time is strenuous activity, it's a general rule because sometimes fighting will involve casting spells and moving around rather than just standing in place and using weapons, and this covers all of it. Taking it to mean you could only do one of them leads to nonsensical results. The odd part there, is that by the rules, you can't take a Dash action, because that's not walking, it's running. Two Dash Actions would be sprinting. I would think sometimes during a fight, people would need to Dash now and again. Maybe that's too strenuous.

The rules seem unclear, and I find no mention of anything about it in the SAC.

I guess I'll just have to make it up for my own rules for my games. I'd say you can cast all the spells you have slots remaining for, and get them all back if you get your Long Rest, and you can cast cantrips until you're blue in the face, but if you cast one more spell after that hour, even a cantrip, you don't get rested. Anything that gives a level of Exhaustion would spoil a Long Rest, so a Berserker Barbarian couldn't use their Frenzy. There are no rules I know of about it, but I would allow using the Dash action freely, but anything more than 15 minutes would be Exhausting I think. My examples of things equally strenuous to an hour spent fighting, walking, running around, and casting spells would be; spending an hour doing any skill checks that use a physical score; like Athletics, Acrobatics, or a Tool Proficiency based on a physical score. I'm on the fence about the Dex based ones, while Acrobatics is pretty clearly something you could get exhausted doing, I don't know that Slight of Hand or Stealth would be that tiring.

Geann, it sounds to me that we agree that the use of the comma in this particular issue changes the entire meaning of the sentence. Here's the only SAC reference I can dig up, which points to RAW - yes you can cast spells during the long rest and not have to restart.

If it helps you, here is how I break the list down at my table, YMMV.

1. 1 hour of walking
2. fighting - any
3. casting spells - I rule this as expending spell slots, not as a ritual.
4. similar adventuring activity

Quote from DxJxC >>

This means you can rest for 7.5 hours, cast a spell, then rest the remaining half an hour to complete the long rest and get the benefits.

If you rest for 7.5 hours and then get up to cast a spell, you've either alreadycompletedthe long rest and reset your spell slots, or broken it and would need to start again -- depending on how much your DM cares about that extra 30 minutes.

Quote from AntonSirius >>

Quote from DxJxC >>

This means you can rest for 7.5 hours, cast a spell, then rest the remaining half an hour to complete the long rest and get the benefits.

If you rest for 7.5 hours and then get up to cast a spell, you've either alreadycompletedthe long rest and reset your spell slots, or broken it and would need to start again -- depending on how much your DM cares about that extra 30 minutes.

You gain no benefit from the long rest until the full 8 hours duration is over, so you cannot have regained spell slots even after 7h59m. You can do 2 hours of light activity during that time, but that time is still required for the long rest.

You can cast spells during a long rest without interrupting it, that is clearly in the rules. Otherwise you couldn't cast ritual spells like identify.

If you still had a 1st level spell slot left over then feel free to cast Mage Armor, Identify, or anything else you like. You'll get the benefit from it.

Does it feel like doing this is within the spirit of the game? Not really. It's much more abusable if you want to cast Conjure Animals or similar and then go into combat within an hour after casting it. I just trust my players not to do this.

Always worth remembering: There is a bit in the DM Guide that reads "There are no rules for when a shipwreck happens, a shipwreck happens when you decide it does." Trying to beat the game by taking advantage of the rules is ultimately pointless. The DM ultimately decides whether you win or not anyway.

Quote from Sanvael >>

Quote from AntonSirius >>

Quote from DxJxC >>

This means you can rest for 7.5 hours, cast a spell, then rest the remaining half an hour to complete the long rest and get the benefits.

If you rest for 7.5 hours and then get up to cast a spell, you've either alreadycompletedthe long rest and reset your spell slots, or broken it and would need to start again -- depending on how much your DM cares about that extra 30 minutes.

You gain no benefit from the long rest until the full 8 hours duration is over, so you cannot have regained spell slots even after 7h59m. You can do 2 hours of light activity during that time, but that time is still required for the long rest.

I have never played in a campaign, nor have I ever seen one played, that marked exactly what time you went to bed/started your long rest, exactly what time in the middle of the night the ambush happened, and exactly what time you got up the next morning. And that's what you're demanding when you split hairs between 7.5 hours and 8.0 hours.

the "one hour" is intended to apply to any of the following examples, applied cumulatively over the rest. So you can fight, cast spells, walk, and do "other adventuring activities" for a cumulative total of 1 hour during the rest and not have to reset it, but none of that would count as "light activity" so it doesn't contribute to rest time. So if you had 4 hours of long rest, then an interrruption that included 15 minutes of spellcasting/walking/fighting/etc), you could continue the rest, but the total amount of time from start to finish would then be 8 hours and 15 minutes (4hours before, 15 minute interruption, 4 hours after).

if you go over the hour, any time before the interruption is lost, so, if you have 4 hours of a long rest, followed by an hour and 15 minutes of walking/spellcasting/fighting, then you would have to restart the whole rest, and the time from "start" to finish would be 13 hours and 15 minutes (4 hours rest, 1 hour 15 minutes interruption, 8 hours of restarted rest)

Most DMs will handwave the minute amount of walking to change watch, move around camp, etc; and casting one spell with an actioncasting is only going to officially interrupt and add 6 seconds to the total time, but things with longer casting times, like find familiar would have to be done before or after a long rest as their casting time would use up the whole allotted "interruption period" forcing a reset of the rest to gain benefit.

(Basically if a goblin group tried to attack the group the wizard could open their eyes, fireball the lot of them, and if they were all killed go right back to sleep and only add 6 seconds to the long rest total time)

Basically, for a DM to truly interrupt a long rest and force a reset would require a substantial amount of fighting or danger, enough to force the party toflee their campsite for over an hour (since most combats last under a minute in game time)

Yeah, in the game I run one of my players, who is an elf/wizard, pretty much does this every long rest as long as he remembers and tells me otherwise that slot is spent.

I never really put much thought into it because of the one-hour rule that is indicated in PHB. The other reason I allow it is it does not make the wizard AC super high, 16, so it's not really game-shattering when the spell is in use. Plus the creatures the party runs across now are a high enough CR that a 16 AC is going to be hit at least 60% of the time and that percentage will only increase as the CR will over time. With low hit points, to begin with, the wizard is will never be upfront in battle maybe it will be effective against range attacks but that is a verylow chance.

Quote from AntonSirius >>

Quote from Sanvael >>

Quote from AntonSirius >>

Quote from DxJxC >>

This means you can rest for 7.5 hours, cast a spell, then rest the remaining half an hour to complete the long rest and get the benefits.

If you rest for 7.5 hours and then get up to cast a spell, you've either alreadycompletedthe long rest and reset your spell slots, or broken it and would need to start again -- depending on how much your DM cares about that extra 30 minutes.

You gain no benefit from the long rest until the full 8 hours duration is over, so you cannot have regained spell slots even after 7h59m. You can do 2 hours of light activity during that time, but that time is still required for the long rest.

I have never played in a campaign, nor have I ever seen one played, that marked exactly what time you went to bed/started your long rest, exactly what time in the middle of the night the ambush happened, and exactly what time you got up the next morning. And that's what you're demanding when you split hairs between 7.5 hours and 8.0 hours.

Well that's kind of required when a player starts saying they want to save their spell slots for a long as possible to be able to cast spells right before they get their slots back, especially something like Mage Armor that has an 8 hour duration. If the long rest is 8pm - 4am, the armor is gone by noon. Now you either have to keep track of what time everything happens so the wizard gets an extra 1st level spell slot, or you essentially double the duration of the spell (that the wizard is already getting for free) just so you don't have to worry about it. OP is actually asking a lot here if there's any concern for balance/fairness and this is part of what makes this kind of thing distasteful to a lot of people.

Quote from scatterbraind >>

Well that's kind of required when a player starts saying they want to save their spell slots for a long as possible to be able to cast spells right before they get their slots back, especially something like Mage Armor that has an 8 hour duration. If the long rest is 8pm - 4am, the armor is gone by noon. Now you either have to keep track of what time everything happens so the wizard gets an extra 1st level spell slot, or you essentially double the duration of the spell (that the wizard is already getting for free) just so you don't have to worry about it. OP is actually asking a lot here if there's any concern for balance/fairness and this is part of what makes this kind of thing distasteful to a lot of people.

I'm even currently playing a 3rd level wizard, and would never try to game it out like that. Mage Armor goes on when it looks like we might be headed into danger, and if we get ambushed, then it'll just take up my first action in the combat while I'm ducking behind a tree for cover or something.

Of course the simplest solution from a DM perspective is to just keep having combat happen later in the day after it's expired, so they have to burn another slot anyway, until the wizard gets the message.

Quote from Geann >>

Kaavel, I have a great track record for missing part of what was said, and I must have missed the bit at the bottom where you mentioned "Combat". That's the only reason I can think of for my first sentence block. The rest would just be me clarifying my own thinking and adding to the system some ideas of my own. Probably not relevant in this forum, but possibly useful to someone, so I'll leave it alone rather than delete my post. Sorry about that.

Nae danger. I was actually referring to the current line of reasoning around the items listed in the "activity — at least 1 hour of walking, fighting, casting spells, or similar adventuring activity — the". Not to you missing the point.

Does the list mean an hour of a bit of everything combined, an hour of each action, or an hour of just walking or any amount of the other things? This is where the DM adjudication comes in, and if you are a player that doesn't agree, address that to your DM. Talk it out with them. Decide how it works in your game. Jeremy Crawford and Mike Mearls don't appear to agree on this either. (See previous SAC link)

Quote from Kaavel >>

Quote from Geann >>

Kaavel, I have a great track record for missing part of what was said, and I must have missed the bit at the bottom where you mentioned "Combat". That's the only reason I can think of for my first sentence block. The rest would just be me clarifying my own thinking and adding to the system some ideas of my own. Probably not relevant in this forum, but possibly useful to someone, so I'll leave it alone rather than delete my post. Sorry about that.

Nae danger. I was actually referring to the current line of reasoning around the items listed in the "activity — at least 1 hour of walking, fighting, casting spells, or similar adventuring activity — the". Not to you missing the point.

Does the list mean an hour of a bit of everything combined, an hour of each action, or an hour of just walking or any amount of the other things? This is where the DM adjudication comes in, and if you are a player that doesn't agree, address that to your DM. Talk it out with them. Decide how it works in your game. Jeremy Crawford and Mike Mearls don't appear to agree on this either. (See previous SAC link)

I always treated this as a combination of up to an hour of time. I don't believe a character must be planted at one spot and cannot move about for eight hours, it's just they cannot exert themselves while taking a rest.

A long rest is a period of extended downtime, at least 8 hours long, during which a character sleeps for at least 6 hours and performs no more than 2 hours of light activity, such as reading, talking, eating, or standing watch. If the rest is interrupted by a period of strenuous activity — at least 1 hour of walking, fighting, casting spells, or similar adventuring activity — the characters must begin the rest again to gain any benefit from it.

At the end of a long rest, a character regains all lost hit points. The character also regains spent Hit Dice, up to a number of dice equal to half of the character's total number of them (minimum of one die). For example, if a character has eight Hit Dice, he or she can regain four spent Hit Dice upon finishing a long rest.

A character can't benefit from more than one long rest in a 24-hour period, and a character must have at least 1 hit point at the start of the rest to gain its benefits.

You need 8 hours to get the benefit of a Long Rest. Six of them must be spent sleeping. There are ways to shorten the time, there are specific rules for it. An Elf of any kind can use 4 hours spent in Trance to get the benefit of a Long Rest. There are similar things for other races. Normally, you've got two hours left over that you can perform "Light Activity", and they define as much as one hour spent; walking, fighting, casting spells, or similar adventuring activities as possible without spoiling a Long Rest. I see this as meaning that you could spend the entire hour walking, or whatever, in any combination so long as it didn't go on for more than an hour, you'd get a Long Rest. So you can spend 6 hours sleeping, one hour doing Strenuous Activity, and another hour of light activity and get a Long Rest.

Obviously, things don't happen in convenient hour long blocks. Stuff happens largely at random, I don't know that anyone would bother to sit there and count the number minutes spent for each activity the player characters did. The idea is to make record keeping easy. A string of different combat encounters during an 8 hour period that takes as much as an hour total, strung out over the entire time or just during one hour has the same total effect. People who were sleeping could wake up, fight or whatever, go back to sleep, and so on, as long as it added up in the end to 6 hours. The 8 hour thing is to allow time for people to set watches, study spells, maintain equipment, cook and eat, whatever else you'd do when you're camping.

It's neat having an Elf in the party. Even when they are in Trance, they are still fairly alert, so if they felt like it, they could stand watch for the whole 8 hours and let everyone else sleep.

Quote from AntonSirius >>

Quote from Sanvael >>

Quote from AntonSirius >>

Quote from DxJxC >>

This means you can rest for 7.5 hours, cast a spell, then rest the remaining half an hour to complete the long rest and get the benefits.

If you rest for 7.5 hours and then get up to cast a spell, you've either alreadycompletedthe long rest and reset your spell slots, or broken it and would need to start again -- depending on how much your DM cares about that extra 30 minutes.

You gain no benefit from the long rest until the full 8 hours duration is over, so you cannot have regained spell slots even after 7h59m. You can do 2 hours of light activity during that time, but that time is still required for the long rest.

I have never played in a campaign, nor have I ever seen one played, that marked exactly what time you went to bed/started your long rest, exactly what time in the middle of the night the ambush happened, and exactly what time you got up the next morning. And that's what you're demanding when you split hairs between 7.5 hours and 8.0 hours.

It's literally essential to do this when the question is "Can I cast Mage Armor 7.5 hours into a long rest and get my spell slot back at 8 hours."

You generally don't have to track things in this way when players aren't trying to munchkin the rules to get advantages that are against the spirit of the rules. My current campaign is set in winter, so there is only daylight from 8am to 5pm, so the party frequently pitch camp at dark and set off at dawn. We've never had to track long rests in this way, but my players aren't trying to gain bonus spell slots.