Concentration and multiple spells

[BenTheJester]

I posted this in the Simple Q&A, but it seems that the answer is quite ambiguous.

When you cast a spell requiring concentration, while concentrating on another spell requiring concentration, at which point does the first spell's effect end to make place for the 2nd?

Example: I have Bane cast on an enemy, and I cast a spell requiring a Save (and Concentration). Does the enemy get the -1d4 to its save (ie the first spell's effect ends when the 2nd one starts), or not (ie the first spell's effect ends when you start casting the 2nd one).

The RAW states that

Casting another spell that requires concentration.
You lose concentration on a spell if you cast another spell that requires concentration. You can't concentrate on two spells at once.

What seems to be ambiguous, is that "if you cast another spell" could be interpreted in different ways:

1- As soon as you begin the Action of casting, it counts as you casting a spell. In my example, Bane would have no effect.

2- Casting a spell is a whole Action, so the new spell takes effect only at the end of my action. In this scenario, I also think Bane wouldn't have an effect.

3- Casting a spell goes in "phases", you start casting, you target an enemy, the enemy fails its save, you apply the effect. In this scenario Bane would apply.

What do you think?

[calebrus]

Ask your DM. :wink:

[Malifice]

In my view, concentration ends once you complete casting the new spell, ending your concentration on any other spell.

Note how at no time are you concentrating on two spells at once, so (to take your example) you cant gain the benefits of your Bane spell AND the new spell at the same time.

[pwykersotz]

In my opinion, the old spell ends prior to the new spell forcing a save.

[cobaltstarfire]

To me that rule is saying that a single casters concentration spells can never overlap. If they could even for a moment the rule would be kind of pointless.

Meaning if you cast bane on someone, then cast another concentration spell, bane is no longer in play.

[BootStrapTommy]

I'd say RAI is the first one.

[Malifice]

No matter what, before you can concentrate on a new spell you have to stop concentrating on the old one.

Old spell ends, then resolve new spell.

[calebrus]

I'd say RAI is the first one.

I agree, but there are two problems with that.
The first is that not every DM cares about RAI. In fact, most players and DMs have gotten so used to the 3e/4e style where the RAI are basically irrelevant and all they care about is the RAW. And by strict RAW, this is ambiguous.
Secondly, the entire purpose of the spell in question is to reduce saves and attack rolls. If a caster wants to spend one of his precious spell slots to lower an enemy's save so that his next slot is more likely to succeed, I wouldn't have a problem with that.
So while I agree that the RAI is that the two would not affect one another at all, in this particular case I would allow it.

Often times there is a disparity between the RAW and the RAI (*and in those cases I personally side on the side of RAI 99% of the time).
In this case there is a disparity between the Intention of a rule and the Intention of a spell.
The RAW and the RAI aren't at odds, as is normally the case. Instead, one set of RAI is at odds with another set of RAI.
So like I said, I would allow it in this case, and determine others on a case by case basis.

[Gritmonger]

I agree, but there are two problems with that.
The first is that not every DM cares about RAI. In fact, most players and DMs have gotten so used to the 3e/4e style where the RAI are basically irrelevant and all they care about is the RAW. And by strict RAW, this is ambiguous.
Secondly, the entire purpose of the spell in question is to reduce saves and attack rolls. If a caster wants to spend one of his precious spell slots to lower an enemy's save so that his next slot is more likely to succeed, I wouldn't have a problem with that.
So while I agree that the RAI is that the two would not affect one another at all, in this particular case I would allow it.

Often times there is a disparity between the RAW and the RAI (*and in those cases I personally side on the side of RAI 99% of the time).
In this case there is a disparity between the Intention of a rule and the Intention of a spell.
The RAW and the RAI aren't at odd, as is normally the case. Instead, One set of RAI is at odds with another set of RAI.
So like I said, I would allow it in this case, and determine others on a case by case basis.

Slippery slope. If they had a non-concentration spell, I'd allow concurrency with a concentration spell. If you allow multiple concentration in one case, where do you stop?

It's like saying a one-car garage is a two-car garage in special cases - the point of this was to do exactly what is being done: force hard choices, or cooperative effects. The magic users, without this restriction on concentration (one at a time) end up not needing other characters as they can simply set up cascades that pummel enemies into unconsciousness with no intervention from anybody else.

It might be useful to be able to have Alter Self going and then Read Thoughts - but by RAW, and RAI - it can't be done. If you want to read thoughts while in disguise, you'd be better off using a real disguise rather than magical disguise.

[calebrus]

Slippery slope. If they had a non-concentration spell, I'd allow concurrency with a concentration spell. If you allow multiple concentration in one case, where do you stop?

Like I said, on a case by case basis.
I normally wouldn't allow it at all, because the RAI is clear as far as I'm concerned.
But in this one particular case, the intention of the spell and the intention of the concentration rules are in contention with each other. So in this one particular case I would allow it, and I highly doubt I'd find another time where I deem two sets of RAI for two different things to be at odds in such a way as to make it murky like this.
So it's not a case of where I stop, and it's more a case of this being a special exception in my mind.

[Gritmonger]

Like I said, on a case by case basis.
I normally wouldn't allow it at all, because the RAI is clear as far as I'm concerned.
But in this one particular case, the intention of the spell and the intention of the concentration rules are in contention with each other. So in this one particular case I would allow it, and I highly doubt I'd find another time where I deem two sets of RAI for two different things to be at odds in such a way as to make it murky like this.
So it's not a case of where I stop, and it's more a case of this being a special exception in my mind.

But not necessarily to your players. There are few really concrete rules and concepts in 5th, and throwing this one out the window will make players wonder "why not this time?" I think this will lead to more consternation among your casters as they push this new non-limit to see where it breaks, and ask why it's arbitrarily this way in this one case. Why not other cases? Are you favoring this class over others? Do only spells that seem like this to you get special treatment?

I think it's inviting conflict and bad feelings.

[calebrus]

But not necessarily to your players. There are few really concrete rules and concepts in 5th, and throwing this one out the window will make players wonder "why not this time?" I think this will lead to more consternation among your casters as they push this new non-limit to see where it breaks, and ask why it's arbitrarily this way in this one case. Why not other cases? Are you favoring this class over others? Do only spells that seem like this to you get special treatment?

I think it's inviting conflict and bad feelings.

If those are the types of players that you have then I'm glad I'm not running your table.

[Malifice]

Like I said, on a case by case basis.
I normally wouldn't allow it at all, because the RAI is clear as far as I'm concerned.
But in this one particular case, the intention of the spell and the intention of the concentration rules are in contention with each other. So in this one particular case I would allow it, and I highly doubt I'd find another time where I deem two sets of RAI for two different things to be at odds in such a way as to make it murky like this.
So it's not a case of where I stop, and it's more a case of this being a special exception in my mind.

Would you make the same exception with hunters mark and swift quiver?

FWIW I disagree with your logic. There is nothing in the spells you mention that infers they break the normal rules for concetration.

[Gritmonger]

If those are the types of players that you have then I'm glad I'm not running your table.

Um, maligning my players is bad form.

[cobaltstarfire]

But in this one particular case, the intention of the spell and the intention of the concentration rules are in contention with each other.

Can you explain how?

Would you then also allow Bless to not require concentration?

Bane (and Bless) specify they must be used/triggered before the spell ends. When you cast another concentration spell the previous spell ends. So Bane (or Bless) go away, whether the effects happened or not. The solution here is for the caster to not try to cast two concentration spells back to back and expect to see the benefits of both, since the rule is pretty clearly saying that you can't have two going at the same time.

[calebrus]

Um, maligning my players is bad form.

I said nothing about your players. I said something about my preference of the types of players that I like to run games for.


Would you make the same exception with hunters mark and swift quiver?

FWIW I disagree with your logic. There is nothing in the spells you mention that infers they break the normal rules for concetration.

Was Hunter's Mark designed to affect a save in any way? No, it wasn't, so obviously it would have no effect. As I said, this one spell kind is a special exception. There might possibly be more, but I don't feel like digging through the spells to find out, so I left the door open for similar exceptions.


Can you explain how?

Sure.
Bane was designed to lower an enemy's attack rolls and saving throws.
The concentration rules exist so that you can't have multiple buffs or debuffs going.
Many spells which require saving throws (and all of those that would arguably be considered the best spells) require concentration. So the spell was designed to do something that, in many cases, it cannot do by the rules. It was designed to lower saving throws, but it doesn't function if the saving throw has a concentration requirement.
The two are at odds.
The rules about concentration make one facet of the spell useless against all non-instantaneous spells.
So the RAI of the spell are at odds with the RAI of the concentration rules. If I were so inclined, I could think of it as a case where the concentration rules are general rules, and the spell would be the specific rule.
As soon as the enemy rolls his save, Bane ends. That's the way that I would play it if and when it comes to the table.
I'm not saying that it doesn't require concentration. I'm saying that I would allow the player to use the spell as it was intended to be used before it ends. If he wants to spend a slot to hopefully lower his opponent's save for the next round (exactly as Bane was intended to do), I have absolutely no problem with that.

[Gritmonger]

I said nothing about your players. I said something about my preference of the types of players that I like to run games for.


You don't know anything about my players. You presume to know, and you denigrate running a table with players "like mine." That's maligning.

And for your information, my players prefer consistency. If that's not "your type of player" I'm not sure what type of player you prefer.

[calebrus]

I said "If those are the type of players that you have," which once again is not saying anything about your players.
Because.... if. If. If those are the types of players that you have.
I said nothing about you or your players. I made a statement that the type of player that you described, one who pushes the DM to see how far he'll bend, is not one that I'd want at the table.
I'm not going to respond to this line of discussion any more.

[cobaltstarfire]

Sure.
Bane was designed to lower an enemy's attack rolls and saving throws.
The concentration rules exist so that you can't have multiple buffs or debuffs going.
Many spells which require saving throws (and all of those that would arguably be considered the best spells) require concentration. So the spell was designed to do something that, in many cases, it cannot do by the rules. It was designed to lower saving throws, but it doesn't function if the saving throw has a concentration requirement.
The two are at odds.



They aren't at odds. One player casts bane, another player casts a spell with a save. Or that same player casts a spell that isn't a concentration spell. There are plenty to chose from.

Or instead you make the baned character take -1d4 on attack rolls.


Bane and the concentration rules are only at odds if you expect one person to be doing all of the stuff, and since the concentration rule is there specifically so that one person is not doing all of the stuff, bane being concentration is not at odds with the rules.

[calebrus]

I'll say it once again, just so it's perfectly clear, and then I'm done arguing about what I would or would not allow. Because frankly, you can play the game how you like and I will play the game how I like. We are in perfect agreement about the RAI.
I'm just saying that....
If he wants to spend a slot to hopefully lower his opponent's save for the next round (exactly as Bane was intended to do), I have absolutely no problem with that.

[Malifice]

Was Hunter's Mark designed to affect a save in any way? No, it wasn't, so obviously it would have no effect. As I said, this one spell kind is a special exception. There might possibly be more, but I don't feel like digging through the spells to find out, so I left the door open for similar exceptions.

No, it was designed to do extra damage.

Have you considered the lower save wasnt designed to help the dude that cast the bane spell, but his allies.

'leader' and all that.

[MadBear]

Not really sure why everyone is arguing with Calebrus here. Seems to me he pointed out a particular place that he's happy to houserule. I can see a good case for either side, and since no one in my group uses bane, its unlikely to come up. Seems too many people are still tied up in telling others "your having badwrongfun". Notice that he stated from the get go, that he isn't proposing that everyone run it this way at their table, or that his is the one and only true path......

[cobaltstarfire]

If he wants to spend a slot to hopefully lower his opponent's save for the next round (exactly as Bane was intended to do), I have absolutely no problem with that.

I have absolutely no problem with it either, as long as the concentration spell being cast next turn is by one of the casters team mates.

I'm not saying Calebrus is engaging in "badwrongfun" I'm objecting to them ignoring the purpose of concentration. If they want to house rule it, that's fine, but it has no place in a thread trying "clarify" how concentration works with spells like the OP is asking for.

[calebrus]

I have absolutely no problem with it either, as long as the concentration spell being cast next turn is by one of the casters team mates.

I'm not saying Calebrus is engaging in "badwrongfun" I'm objecting to them ignoring the purpose of concentration. If they want to house rule it, that's fine, but it has no place in a thread trying "clarify" how concentration works with spells like the OP is asking for.

Go look at the second post in the thread.
The fact of the matter is that, while you may interpret a certain order to the events here, the PHB does not state them clearly.
The question was: What is the order?
The RAW is ambiguous, so people are discussing RAI. The fact that the RAW is ambiguous and the fact that people are discussing RAI, makes this the quintessential place for people to discuss where and how and why they might house rule this situation. So, yes, there is a place for it. In fact, this is the perfect place for it. There will never be a better place for it.
But thanks for sharing your opinion.

[Envyus]

He can change how the spell works that's fine. But RAW does not even come close to supporting his interpretation of Bane lowering a creatures save for another concentration spell cast by the same caster.

Once you cast a new concentration spell the one you were concentrating on ends on the spot. There is no room for interpretation about RAW or RAI here. Nothing is contradicted ether. Meaning this change you allow is a houserule not supported by RAI or RAW.

[Goodberry]

Page 203 of the PHB clearly states, "You can't concentrate on two spells at once." Anything else is a house rule.

[Malifice]

Page 203 of the PHB clearly states, "You can't concentrate on two spells at once." Anything else is a house rule.

Just before that it states:

PHB pg 203

You lose concentration on a spell if you cast another spell that requires concentration.

So when you cast another spell that requires concentration, you lose your concentration on any other spell that you have going. Its effects end the instant you cast your other spell.

You stop concentrating on one spell (and it ends) and start concentrating on another afterwards. RAW and RAI are clear. RAF or RAIBTDM are your call.

[Fyorl]

If he wants to spend a slot to hopefully lower his opponent's save for the next round (exactly as Bane was intended to do), I have absolutely no problem with that.
Sorry if this is derailing the topic a bit. Your houserule seems totally reasonable but it just occurred to me that a perhaps less fiddly way to accomplish this would be to houserule back in the old Cleric spell 'Doom'. I only really remember it from Baldur's Gate so I assume it's in 2e at least but it's a level 1, single-target spell that wouldn't require concentration and gives the target -2 to attack rolls, saves and ability checks for 1 minute (maybe nerf that to 1 or 2 rounds though with longer durations for higher spell slots). Or maybe houserule back in Greater Malison if you really want the AoE debuff without concentration (it's a level 5 spell iirc which seems reasonable for its power).

[Mr.Moron]

It ends at the latest possible point where it prevents the two spells from interacting with, stacking and/or benefiting from each other. This timing may be different depending on the particular spells involved.

In the bane scenario I'd rule it ends when the save is made. However in some scenario where say the new spell wouldn't interact with the concentration spell until after the save is made, if the save is successful (and you never begin concentrating on the new spell), the previous spell never ends.

[pwykersotz]

It ends at the latest possible point where it prevents the two spells from interacting with, stacking and/or benefiting from each other. This timing may be different depending on the particular spells involved.

In the bane scenario I'd rule it ends when the save is made. However in some scenario where say the new spell wouldn't interact with the concentration spell until after the save is made, if the save is successful (and you never begin concentrating on the new spell), the previous spell never ends.

Interesting...darn it if I kind of like that interpretation. I'll have to think on it some more.

[Chronos]

The RAW is not ambiguous. I'll repeat what I said in the Q&A thread: The only way you could get the Bane penalty on the save versus the second spell would be if you rule that a victim rolls a save versus a spell before the spell is cast.

[Mr.Moron]

Interesting...darn it if I kind of like that interpretation. I'll have to think on it some more.

If it helps my motivation in doing it this way is this:

The concentration rules are clearly meant as a response to the "Christmas Tree" effect in previous editions, it's there to prevent the layering of spell effects. I don't think it represents any particularly fundamental underlying rules of magic or something in-universe it's just a meta-consideration. A meta consideration I (mostly), agree with.

This means I only need to extend the rule so far as it keeps that meta-consideration in place but not really further. Losing your spell to save is a feel bad, losing it and your previous spell to the save would be a double feel-bad. Since nothing is gained in terms of preventing spell layering by the double spell loss I see no reason to enforce it.

This makes the casting of concentration spell perhaps something of a smaller risk than it would be under a more standard interpretation, but since it does little or nothing to the power ceiling or floor it's not that huge a "balance" consideration despite the lower risk.

[Gritmonger]

This is a decent consideration - if you never start concentrating on a new spell due to save, it never has a chance to knock out the old spell. Magic and non meta-wise, there is nothing preventing you from casting non concentration spells while you are concentrating, so it represents a tax on your attention - if you want to fluff it a little, you could have the caster make a concentration check in the event of a new concentration spell failing to keep the old one going instead.

[heavyfuel]

I'll stick to my reply in the RAW thread. A spell is only cast when you finish casting it, since no spell can be cast imediately, they all have a casting time. The effects then take place afterwards (so Bane won't apply)

If the casting of the spell is interrupted, it isn't cast, and you don't waste your spell slot, since this only occurs when you actually cast the spell, not when you begin casting it.


When a character casts a spell, he or she expends a slot of that spell’s level or higher



The RAW is not ambiguous. I'll repeat what I said in the Q&A thread: The only way you could get the Bane penalty on the save versus the second spell would be if you rule that a victim rolls a save versus a spell before the spell is cast.

Pretty much, the RAW is clear. Don't know why people are arguing so much about this fact

[calebrus]

Interesting...darn it if I kind of like that interpretation. I'll have to think on it some more.

That's how I work the smite line of spells as well. If the smite spell has an instantaneous rider (instead of a rider that continues) and the first attack made is the one that hits, there's nothing to concentrate on, so concentration on any previous spell is not interrupted.
Unless you actually begin concentrating on another spell, any previous concentration is not interrupted.
Again, house rule.


Pretty much, the RAW is clear. Don't know why people are arguing so much about this fact

RAW is not clear. It doesn't specify exactly when the change in concentration occurs. That's kind of the entire point of this whole thread.
Your interpretation may be clear. The RAI may be clear. But the RAW is ambiguous.
And since the RAW is ambiguous, and the RAI (which is clear, while the RAW is not) makes things not work as we feel they should in some cases, we are discussing house rules.

[Mellack]

RAW is not clear. It doesn't specify exactly when the change in concentration occurs. That's kind of the entire point of this whole thread.
Your interpretation may be clear. The RAI may be clear. But the RAW is ambiguous.
And since the RAW is ambiguous, and the RAI (which is clear, while the RAW is not) makes things not work as we feel they should in some cases, we are discussing house rules.

Raw is not clear on when concentration starts, but that is not needed to answer the question. RAW says you lose concentration when you CAST another spell that is also a concentration spell. Not when you have to start concentrating on it. So as stated above by another poster, unless you are requiring saves before people cast the spell, there is no way Bane can still be going when they make their saves.

[mephnick]

This is a case where RAW shouldn't matter in the slightest.

The entire idea of this massive change to the spell rules was to prevent two concentration spells at the same time. Don't try and break it. Please.

[calebrus]

So as stated above by another poster, unless you are requiring saves before people cast the spell, there is no way Bane can still be going when they make their saves.

Or, you know, unless you wanted Bane to work as it was intended to work and not make it basically useless for one of its purposes 50% of the time.

[Gritmonger]

This is a case where RAW shouldn't matter in the slightest.

The entire idea of this massive change to the spell rules was to prevent two concentration spells at the same time. Don't try and break it. Please.

In this wise it is a little similar to attunement, another mechanic introduced to somewhat limit what can become an abusive situation. DMs can modify if they see fit, but it removes the system from culpability when questions of balance arise as a result, and would, like modifications to concentration, end up being not the core rules and a purely homebrew mechanic, as it isn't an optional variant to not have concentration work as an exclusionary property.

[pwykersotz]

So...that was interesting. I talked to two of my players and they gave me completely negative feedback on the possible changes. They said that anything other than the rules of immediate ending to even attempt a new concentration spell feel overpowered and unlike concentration at all. They're perfectly happy with their power level as-is and don't need any tweaking in their favor.

So there's that, I guess. If it ain't broke, don't fix it. :smalltongue:

[Mellack]

Or, you know, unless you wanted Bane to work as it was intended to work and not make it basically useless for one of its purposes 50% of the time.

I believe you mean the way YOU think it was intended. I do not agree with your RAI. I believe they meant for a single caster to not be able to do that, giving the reason for the concentration concept in the first place. You are basically taking your own desires and changing the game to fit them. That is perfectly acceptable, and even encouraged. But that is not what the rules say or how I think they were intended. If you have some inside knowledge of what the designers intended with this specific rule, please share.

[calebrus]

I believe you mean the way YOU think it was intended. I do not agree with your RAI. I believe they meant for a single caster to not be able to do that, giving the reason for the concentration concept in the first place. You are basically taking your own desires and changing the game to fit them. That is perfectly acceptable, and even encouraged. But that is not what the rules say or how I think they were intended. If you have some inside knowledge of what the designers intended with this specific rule, please share.

No, the spell was designed to lower an enemy's attack rolls and saving throws.
This is indisputable.
But when you cast a spell that requires concentration against an enemy, and basically every non-instantaneous spell which can target an enemy requires concentration, the Bane spell fails at its intended purpose.
So I will allow the spell to function as it was intended to function.

[Mellack]

No, the spell was designed to lower an enemy's attack rolls and saving throws.
This is indisputable.
But when you cast a spell that requires concentration against an enemy, and basically every non-instantaneous spell which can target an enemy requires concentration, the Bane spell fails at its intended purpose.
So I will allow the spell to function as it was intended to function.

Your assumption is that it is expected to lower the enemies saving throws against other concentration spells cast by the same caster. That is in no way an expectation in this edition. You are making presumptions that are not supported. You have yet to show that their was any intention by the designers for these spells to work together, and the written rules suggest their intensions were to disallow such combinations. Bane lowers saves for your teammates and any instant spells you may cast, that is plenty.

[Envyus]

Your assumption is that it is expected to lower the enemies saving throws against other concentration spells cast by the same caster. That is in no way an expectation in this edition. You are making presumptions that are not supported. You have yet to show that their was any intention by the designers for these spells to work together, and the written rules suggest their intensions were to disallow such combinations. Bane lowers saves for your teammates and any instant spells you may cast, that is plenty.

Indeed. Bane is doing exactly what it's supposed to do.

[calebrus]

I don't need to show where a designer specifically stated anything.
We were discussing a house rule on the matter, and I explained why, how, and when I would allow something. This is not even remotely about the RAW, so I don't need to justify anything to you.

I explained why I would allow the situation in question.
If you have a problem with it, then it is exactly that: your problem.

[Mellack]

I don't need to show where a designer specifically stated anything.
We were discussing a house rule on the matter, and I explained why, how, and when I would allow something. This is not even remotely about the RAW, so I don't need to justify anything to you.

I explained why I would allow the situation in question.
If you have a problem with it, then it is exactly that: your problem.

I said I had no problem with you using any house rules you desired. I was responding to your claim

RAW is not clear. It doesn't specify exactly when the change in concentration occurs. That's kind of the entire point of this whole thread.
Your interpretation may be clear. The RAI may be clear. But the RAW is ambiguous.
And since the RAW is ambiguous, and the RAI (which is clear, while the RAW is not) makes things not work as we feel they should in some cases, we are discussing house rules.

You claim the RAI is clear. I disagree on that. You claim to know the intent, and I asked you to show how you determined that since all evidence seem to be contrary to what you think RAI is. I did not say you are playing wrong, or that you should not rule at your table however you find best. I will say when you attempt to overstate your position as being anything other than your opinion by trying to use some reference to intention that is not there.

[calebrus]

So you're saying that Bane is not intended to lower saving throws?
Because I'm pretty sure that this isn't what you're saying.
So we can agree, Bane is intended to lower an enemy's saving throw.
Good.
So I allow the spell to be used as it was intended to be used.
No more, no less.

[Mellack]

So you're saying that Bane is not intended to lower saving throws?
Because I'm pretty sure that this isn't what you're saying.
So we can agree, Bane is intended to lower an enemy's saving throw.
Good.
So I allow the spell to be used as it was intended to be used.
No more, no less.

Please read what I said again. Bane is intended to lower an enemy's saving throws against all of your team's powers and any instant spells the concentration holder casts. It is not been shown to be intended to lower the saves against the concentration holder's further concentration spells.

[calebrus]

Please read what I said again. Bane is intended to lower an enemy's saving throws against all of your team's powers and any instant spells the concentration holder casts. It is not been shown to be intended to lower the saves against the concentration holder's further concentration spells.

Please read what I wrote again. If you have a problem with the way that I interpret and rule something, that's your problem.

[jkat718]

Although I personally disagree with them, I can definitely see where calebrus is coming from. I wouldn't use his house rule except in certain cases, such as a party with only one spellcaster, but I do see the rule's merits.

[Talderas]

1- As soon as you begin the Action of casting, it counts as you casting a spell. In my example, Bane would have no effect.

2- Casting a spell is a whole Action, so the new spell takes effect only at the end of my action. In this scenario, I also think Bane wouldn't have an effect.

3- Casting a spell goes in "phases", you start casting, you target an enemy, the enemy fails its save, you apply the effect. In this scenario Bane would apply.

Concentration is lost when you cast a spell and not because you are casting a spell. The spell must be successfully cast to create the conditions under which concentration becomes required. A spell interrupted by Counterspell will not cause you to lose concentration you're already holding because you don't cast a spell. Scenario #1 is definitely not the case however that introduces the problem that you brought up with bane. Your third scenario is undoubtedly the nature of how spells work and I say this mostly based on the existence of counterspell and other abilities that can be used while a spell is being cast. Casting a spell proceeds in phases. It is a reasonable assumption that the window to counterspell is open as long as the spell hasn't been cast. Under that assumption the only outcome that doesn't create a weird paradox is that the spell is cast and then the effects take place. Otherwise if they spell is considered cast after effects take place then I could counterspell when I see that party members have failed saves.

Thus to address your situation with bane specifically, I believe the rules say that you do not lose concentration by casting a spell that requires concentration and you only lose concentration once you have finished casting the spell. However the spells effects do not take effect until after you lose concentration on your previous spell. Bane would not give any penalty to the target's save against your second concentration spell.