Do all spells with durations require concentration and prevent casting other non-instant spells?

Question

How does spell casting work with regards to concentration and multiple spells?

The other players in my group are arguing that duration-based spells require concentration and the casting of any other duration-based spell would cause the first to disappear.

For example, they say that if I cast Produce Flame, that is the only spell I can cast until I have used the spell entirely, or if I choose to cast another spell such as Flaming Sphere then Produce Flame's effects end as I'm no longer concentrating on it, even though the duration specified has not ended.

I find this interpretation extremely limiting on spellcasting, especially as a druid, as it means I can't ever use multiple spells that have durations of more than one turn, like Summon Nature's Ally, Entangle, Flaming Sphere and others.

The way I understand it is that only spells specifying concentration in its use, such as Summon Swarm, require the user to actively concentrate on the spell, and that only another of these concentration-based spells would cause the first to cease and that the casting and use of multiple non-concentration spells was fine.

Answer 1

For reference, here are the rules for duration.

They're arguing that non instant spells require concentration and the casting of any other non instant spell would cause the first to disappear.

I can't find anything in the RAW to support this. Let's call it a house rule for the sake of discussion.

(I can't find anything that explicitly refutes it either, but that's for the same reason that I can't find anything to refute the idea that every time a character casts a spell their player has to light a big dribbly candle and use it to melt a D4)

Watching how that house rule interacts with obvious things shows it to be ridiculous.

Mage Armor has a duration of 1 hour/level. It is traditional for a wizard to cast it on themselves before going into danger. There isn't a whole lot of point in doing that if they won't be able to do anything other than shoot things with their crossbow (or if the rules for maintaining a spell that requires concentration are used, not even that since they would only get move and free actions as the standard action would be eaten by maintaining Mage Armor).

Gentle Repose has a duration of One day/level. When a Wizard gets access to the spell at level 5, that would allow them to maintain it for 5 days … providing they could concentrate, which would involve not going to sleep, for that long.

Then we get Permanent Image with a duration of Permanent. It's rather pointless if it goes away as soon as you stop spending a standard action every round to keep it.

Then we have spells with a duration of concentration (or concentration + 1 round, etc). It makes no sense to define a spell with a duration of concentration if all spells require concentration.

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Your understanding is correct. The other players are wrong. If a spell doesn't have a duration that mentions concentration, then it is a Fire & Forget spell.

Answer 2

Several correct answers here, and for that matter, your question itself was already correct. I find citing the rules here a little awkward, because they don’t directly address this—there’s not really any way to demonstrate that this rule doesn’t exist. You can check the duration section of the magic overview, and you won’t find it there. You won’t find it anywhere. But short of quoting the entire 3.5e corpus and saying “it’s not in there,” there’s not really anything to quote for this.

For the sake of making your case, though, I think there’s a phenomenal “case-in-point” to look to here:

Summon Swarm

[…]
Duration: Concentration + 2 rounds

This spell explicitly continues to be in effect after you have stopped concentrating. For 2 rounds once you’re done concentrating, you are free to do other things, including casting other spells, and the swarm will still be around, doing its thing.

Now compare that to nearly any other spell:

Mage Armor

[…]
Casting Time: 1 standard action
[…]
Duration: 1 hour/level (D)

The word “concentration” doesn’t appear. That means, not only do you not need to concentrate on it for hours on end, you can’t do so (to any meaningful effect). You concentrate on the spell for 1 standard action—while casting it, for its casting time—and then when you finish concentrating on it, that is finish casting it, it lasts for 1 hour/level. It as if it said “Duration: (Concentration, up to 0 rounds) + 1 hour/level (D),” only they don’t say that because that’s ridiculous.

Notably, D&D 3.5e spellcasters are immensely strong. You could still make an overpowered spellcaster with this as a houserule. That doesn’t mean it’s good to nerf spellcasters in this way, however: while there are still spellcaster builds that would be overpowered, there are far fewer. You’d basically have to make a mailman, which basically forces you to be sorcerer or wizard (or maybe a warlock, for a weaker version of a similar idea), and even then pigeonholes you into very specific approaches to those classes.

Answer 3

I believe your friends might be confusing spells with the concentrate duration on them.

Concentration

The spell lasts as long as you concentrate on it. Concentrating to maintain a spell is a standard action that does not provoke attacks of opportunity. Anything that could break your concentration when casting a spell can also break your concentration while you’re maintaining one, causing the spell to end.

You can’t cast a spell while concentrating on another one. Sometimes a spell lasts for a short time after you cease concentrating.

As an example. You cast a spell with the duration:

Concentrate + 1d6 + 1

What this means is you can keep the spell going as long as you concentrate but when you stop concentrating on it the spell continues for 1d6+1 rounds.

Answer 4

A duration based spell only requires concentration if it's specifically listed as Duration: Concentration.

This means the spell has an effectively limitless duration (unless otherwise stated) at the cost of not being able to do anything more serious than a single move action (concentrating on a concentration duration spell takes up your standard action each round), and having to make a concentration check anytime anything that would trigger a concentration check occurs or the spell ends.

In this case, Produce Flame is not a concentration spell.

Duration: 1 Min/cLvl (D)(S).

(the D stands for dismissable so you can choose to end it prematurely if you wish. The (S) means there's something special about the duration. In this case, using Produce Flame to attack reduces your effective duration by 1 minute per attack, ending the spell at the end of the attack action if it's duration is reduce to 0 or lower. Produce Flame could not be used to attack if it was a concentration duration, as attacking is a standard action and would end the spell)

By Contrast, Detect Magic is Duration: Concentration (Limit: 1 round/clvl) (lasts until concentration is broken OR 1 round/clvl at most)

Or the warlock invocation Summon Swarm, which is Duration: Concentration +2 rounds (lasts for as long as you concentrate on it, +2 rounds after concentration ends).

Answer 5

If you are playing 3.5 D&D, according to the PHB, all spells, unless specifically stated otherwise, require concentration to cast:

Concentration

You must concentrate to cast a spell. If you can’t concentrate you can’t cast a spell. If you start casting a spell but something interferes with your concentration you must make a Concentration check or lose the spell. The check’s DC depends on what is threatening your concentration (see the Concentration skill). If you fail, the spell fizzles with no effect. If you prepare spells, it is lost from preparation. If you cast at will, it counts against your daily limit of spells even though you did not cast it successfully.

Further, any spells that require continued concentration may require subsequent concentration checks to maintain that spell for another round. Lastly, according to traditional 3.5 rules, you cannot cast another spell while you are currently concentrating for another duration spell.

Concentrating to Maintain a Spell

Some spells require continued concentration to keep them going. Concentrating to maintain a spell is a standard action that doesn’t provoke an attack of opportunity. Anything that could break your concentration when casting a spell can keep you from concentrating to maintain a spell. If your concentration breaks, the spell ends. You can’t cast a spell while concentrating on another one. Sometimes a spell lasts for a short time after you cease concentrating."

I use a house rule that allows up to three continuous concentrated spells, with a caveat of increased concentration DC.