bonus action spells.

[iTreeby]

Recently I had a DM who had an evil guy escape by casting misty step in the same round as a darkness spell. This violates the rule that if you use a bonus action to cast a spell, the only other spell you can cast that turn must be a cantrip. It's a new system to everyone so it's an easy mistake to make given the seemingly arbitrary nature of the rule. It seems like the rule is in place only to enable sorcerers quicken meta-magic but as I am away from the books at the moment I am not sure that is even the case.

So anyway, my question is this: is there a way could you cast a bonus action spell and a non cantrip spell in the same round? Fighters can apparently cast two spells in a round with action surge but i'm not sure they could do a bonus action and regular action spells, sorcerer meta-magic perhaps works, maybe a ring of spell storing could do it...

Bonus question: if there are no ways to get around the spell limit thing, how powerful of an effect would it be to homebrew a magic item that simply lets you bypass the rule (but does not grant extra spells or change casting times)?

Thanks in advance.

[Kryx]

There is no specific rule that I know of that beats the general rule:


A spell cast with a bonus action is especially swift. You must use a bonus action on your turn to cast the spell, provided that you haven’t already taken a bonus action this turn. You can’t cast another spell during the same turn, except for a cantrip with a casting time of 1 action.

If you chose to houserule it so that multiple spells could be cast in a round it would surely increase the power level of any bonus action spell and would increase sorcerer's burst ability immensely.
I would highly recommend against this, except for NPCs in rare cases (see Lair Actions, Legendary Actions).

[cmac]

I wouldn't allow multiple spells being cast, but I have allowed a caster to make a melee attack as primary action and follow up with a spell cast as a bonus action. My general rule in this situation is that the bonus action spell cast has to be at spell slot level. So basically, you can't power up a lvl 3 fireball to nuke a guy after you already got a shot in with melee. If you wanted to allow the power up, I would consider giving the target an advantage on saves to balance it out.

If you don't want everyone to have this, homebrew a feat for your table that allows it or expand War Caster feat to include it. I only add the feat if I want PCs to have an ability that I don't want hostile NPCs to have.

If I were to allow multiple spells, I might allow the cantrip as a follow up bonus action. My thought process is that the bonus action has to be really quick, almost reflexive, so only spells that a caster is really familiar with could be cast with that little thought and concentration. This makes the order significant, so you have to have the actual leveled spell cast first, then the cantrip second. But I might also consider penalizing this. Advantage on save rolls and/ or making it a requirement that the leveled spell be cast at level. If I started to notice this ability was really overpowered, I might tack on some kind of feedback damage (1d4) to discourage overuse of this ability to help keep the original balance intact.

[Kryx]

If I were to allow multiple spells, I might allow the cantrip as a follow up bonus action.

This is RAW, as quoted above.

[holygroundj]

I wouldn't allow multiple spells being cast, but I have allowed a caster to make a melee attack as primary action and follow up with a spell cast as a bonus action. My general rule in this situation is that the bonus action spell cast has to be at spell slot level. So basically, you can't power up a lvl 3 fireball to nuke a guy after you already got a shot in with melee. If you wanted to allow the power up, I would consider giving the target an advantage on saves to balance it out.

If you don't want everyone to have this, homebrew a feat for your table that allows it or expand War Caster feat to include it. I only add the feat if I want PCs to have an ability that I don't want hostile NPCs to have.

If I were to allow multiple spells, I might allow the cantrip as a follow up bonus action. My thought process is that the bonus action has to be really quick, almost reflexive, so only spells that a caster is really familiar with could be cast with that little thought and concentration. This makes the order significant, so you have to have the actual leveled spell cast first, then the cantrip second. But I might also consider penalizing this. Advantage on save rolls and/ or making it a requirement that the leveled spell be cast at level. If I started to notice this ability was really overpowered, I might tack on some kind of feedback damage (1d4) to discourage overuse of this ability to help keep the original balance intact.

Your house rule is actually just RAW for the first situation. If you cast a spell as a bonus action, you can use your main action for anything normally allowed other than a spell. So RAW you can make an attack, or cast a cantrip, and cast, say, healing word after or before.

However, casting an action spell does not allow you to move your cantrip to a bonus action.

[pibby]

The rule is that you can only cast 1 spell per turn, but not per round! So you can still cast reaction spells and readied spells if you had casted a bonus action spell on your turn. Just tell your DM that your ready action goes off when another character does something. That way your readied action spell goes off immediately after your turn.

[Shadow]

So anyway, my question is this: is there a way could you cast a bonus action spell and a non cantrip spell in the same round? Fighters can apparently cast two spells in a round with action surge but i'm not sure they could do a bonus action and regular action spells, sorcerer meta-magic perhaps works, maybe a ring of spell storing could do it...

Fighter's Action Surge is the answer you're looking for.

I'm going to paraphrase here, not quote, because that gets this particular point across better. Lawyers may argue, but the fact that this is the intent is 100% crystal clear. So, paraphrasing:
General spellcasting rules state that you can only use one spell slot per turn.
These general spellcasting rules are not superseded by the bonus action rules allowing a cantrip as an action, because you are still only using one spell slot on that turn. So don't think of that as a specific rule, think of that as a clarification. If you use a spell slot on your bonus action, you may use your action to cast a cantrip (and you've still only spent one single slot that turn, which still follows the general rule).
The Fighter's Action Surge is a specific rule which allows one free action above and beyond what you can normally do, which can be anything that your action could normally be. It breaks normal action economy. That is the ability's entire purpose for existing. You take your normal actions for the round, and then you get one more action.

So a fighter 2 / caster X could cast three spells on his turn. One bonus action spell, one cantrip, and one action surge spell (which can be anything).

[Alucard2099]

Fighter's Action Surge is the answer you're looking for.

I'm going to paraphrase here, not quote, because that gets this particular point across better. Lawyers may argue, but the fact that this is the intent is 100% crystal clear. So, paraphrasing:
General spellcasting rules state that you can only use one spell slot per turn.
These general spellcasting rules are not superseded by the bonus action rules allowing a cantrip as an action, because you are still only using one spell slot on that turn. So don't think of that as a specific rule, think of that as a clarification. If you use a spell slot on your bonus action, you may use your action to cast a cantrip (and you've still only spent one single slot that turn, which still follows the general rule).
The Fighter's Action Surge is a specific rule which allows one free action above and beyond what you can normally do, which can be anything that your action could normally be. It breaks normal action economy. That is the ability's entire purpose for existing. You take your normal actions for the round, and then you get one more action.

So a fighter 2 / caster X could cast three spells on his turn. One bonus action spell, one cantrip, and one action surge spell (which can be anything).


Well said!

[Kryx]

The Fighter's Action Surge is a specific rule which allows one free action above and beyond what you can normally do, which can be anything that your action could normally be. It breaks normal action economy. That is the ability's entire purpose for existing. You take your normal actions for the round, and then you get one more action.

So a fighter 2 / caster X could cast three spells on his turn. One bonus action spell, one cantrip, and one action surge spell (which can be anything).

The fighter's action surge, however, does not specifically allow you to cast another spell - it never overwrites the general rule of "1 spell per turn" unless I've missed something..

[Shadow]

The fighter's action surge, however, does not specifically allow you to cast another spell - it never overwrites the general rule of "1 spell per turn" unless I've missed something..

I have already addressed your concerns.


I'm going to paraphrase here, not quote, because that gets this particular point across better. Lawyers may argue, but the fact that this is the intent is 100% crystal clear. So, paraphrasing:.

And yes, it does overwrite that general rule, because it is a specific rule.
Spellcasting rules =- general rules.
Action Surge = specific rules.
Specific trumps general.
Action surge can be anything which can normally be done with an action. It breaks action economy, as I have said. That is its entire purpose for existing, as I have said.

[Kryx]

this is the intent is 100% crystal clear.

So this is not RAW, k.

I'm not sure where I stand on the issue - I'd have to do more research. I just thought you had some RAW, dev quote, or something else.


EDIT: Responding to your edit:


And yes, it does overwrite that general rule, because it is a specific rule.
Spellcasting rules =- general rules.
Action Surge = specific rules.
Specific trumps general.
Action surge can be anything which can normally be done with an action. It breaks action economy, as I have said. That is its entire purpose for existing, as I have said.

It says you get another action, not the ability to bypass the 1 spell per turn. The spellcasting limit isn't limited on the action economy, it's limited by the "1 spell per turn" clause or else you would see many action + bonus spell rounds.

[Shadow]

So this is not RAW, k.

I'm not sure where I stand on the issue - I'd have to do more research. I just thought you had some RAW, dev quote, or something else.

It says you get another action, not the ability to bypass the 1 spell per turn. The spellcasting limit isn't limited on the action economy, it's limited by the "1 spell per turn" clause or else you would see many action + bonus spell rounds.

Regarding action surge?
You just posted a link to sageadvice in a different thread. The answer you're looking for is there.

http://www.sageadvice.eu/2014/09/23/action-surge-spell-2/

Remember, specific trumps general.
Name something you can do with one action. You can do that one thing you named regardless of what else you have done on your turn if that action is taken via Action Surge.
Action surge even states right in the text that you are pushing yourself beyond your normal limits.
That is why action surge exists.

[Kryx]

Ya, the intent is there.
http://www.sageadvice.eu/2014/09/19/action-surge-spell/
http://www.sageadvice.eu/2014/09/23/action-surge-spell-2/

Good enough for me.

[Yoroichi]

I read the tweet, and have also followed the other thread regarding action surge, but it just seems ridiculous that ONLY a second level fighter can cast 2 non cantrip spells in one turn and the sorcerer with all his metamagic cant!

I am not sure how any of this makes sense to you guys, but in my table i would not allow the fighter to cast 2 non cantrip spells with action surge.

And as for the specific vs general argument, can the fighter also fly? Which obviously is beyond his normal capabilities..
With your reasoning i d rule yes, its something extraordinary he can do (that is also not specifically forbidden on the action surge list), so with action surge he should be able to do it. Hell, he might as well cast Gate, why not mind you>?

[Flashy]

I am not sure how any of this makes sense to you guys, but in my table i would not allow the fighter to cast 2 non cantrip spells with action surge.

And as for the specific vs general argument, can the fighter also fly? Which obviously is beyond his normal capabilities..
With your reasoning i d rule yes, its something extraordinary he can do (that is also not specifically forbidden on the action surge list), so with action surge he should be able to do it. Hell, he might as well cast Gate, why not mind you>?

I think the point is not that a 2nd level fighter can cast two spells out of nowhere, but that a character with two levels of fighter AND pre-existing spell slots (from multiclassing, eldritch knight, etc) could use an action surge to cast two of those spells on the same turn.

[Yoroichi]

I think the point is not that a 2nd level fighter can cast two spells out of nowhere, but that a character with two levels of fighter AND pre-existing spell slots (from multiclassing, eldritch knight, etc) could use an action surge to cast two of those spells on the same turn.

I have understood the point, and can not argue regarding RAW, plus the tweet.

But in your opinion, does it seem reasonable that an eldritch knight can cast 2 non 0 spells/turn but a sorcerer can not unless he multiclasses to a fighter?

[Shadow]

I have understood the point, and can not argue regarding RAW, plus the tweet.

But in your opinion, does it seem reasonable that an eldritch knight can cast 2 non 0 spells/turn but a sorcerer can not unless he multiclasses to a fighter?

An EK can use two slots once per short rest, maybe a few times per day.
A sorcerer can use one slot and a cantrip (or two cantrips) every single round, all day long.

[Kryx]

But in your opinion, does it seem reasonable that an eldritch knight can cast 2 non 0 spells/turn but a sorcerer can not unless he multiclasses to a fighter?

I agree that the fluff doesn't make great sense, but somtimes it's best to just accept things are simply mechanical choices, not fluff based.

Besides a 2 lvl dip has been shown in other threads to generally be worse mechanically as you're behind a full caster in spell slots, spell level, etc.

[Yoroichi]

Indeed I am only arguing fluff-wise, i just can't get it...

RAW it is clear what happens.

Shadow your point is invalid. Not arguing usefulness or strength or balance. My fluffrgument was that an adventurer that specializes in magic, with an inherent magic ability, probably devoting his life to it that is capable of extensive magical abilities not available to dedicated magic researchers, such as wizards, can not do something a fighter, who studies magic on the side, can do.

[Kryx]

fluffrgument

Amazing new word that shall be deployed!

[Yoroichi]

Amazing new word that shall be deployed!


Oh you ! :smalltongue:

[iTreeby]

Thank you all for your replies! this thread has been a boon to my understanding.

so,

The rule is that you can only cast 1 spell per turn, but not per round! So you can still cast reaction spells and readied spells if you had casted a bonus action spell on your turn. Just tell your DM that your ready action goes off when another character does something. That way your readied action spell goes off immediately after your turn.

I think this does not work because to cast a ready action spell you have to cast it on your turn and concentrate until it triggers.

Also, no one has answered the bonus question! I could see a hypothetical ring of castyness that lets you cast a single additional non cantrip spell a turn as a legendary magic item simply because it's munchkin as hell and makes you not have to take two levels of fighter. but the item is still broke as hell... if it only let you do it once per day AND required attunement, what rarity would you make it? probably still legendary but i suppose the real question is "is it still too game breaking to allow the ring of castyness and if so what other restrictions would you place on such an item?"

Y'all are super.

[Kryx]

I think this does not work because to cast a ready action spell you have to cast it on your turn and concentrate until it triggers.

To be fair the rule is misquoted (due to most people summarizing it).


A spell cast with a bonus action is especially swift. You must use a bonus action on your turn to cast the spell, provided that you haven’t already taken a bonus action this turn. You can’t cast another spell during the same turn, except for a cantrip with a casting time of 1 action.

Which means you are unable to take a reaction on your turn. (Who would you be reacting to, anyways? Someone using their reaction to react to your spell?)
However you can cast a reaction during the round (other people's turns).

Your quote is referring to readying an action to cast a spell, not using your reaction to cast a spell in reaction to some stimulus which is entirely different.



no one has answered the bonus question! I could see a hypothetical ring of castyness that lets you cast a single additional non cantrip spell a turn as a legendary magic item simply because it's munchkin as hell and makes you not have to take two levels of fighter. but the item is still broke as hell... if it only let you do it once per day AND required attunement, what rarity would you make it? probably still legendary but i suppose the real question is "is it still too game breaking to allow the ring of castyness and if so what other restrictions would you place on such an item?"

I don't think the item should exist, period.

The rules are intended to limit the burst of spells. People who take 2 fighter make a significant sacrifice to do so. I would also not allow a magic item to allow you to have multiple concentration spells going at one.
Both of these break core limits on spellcasting.

[IndirectLemon]

I have understood the point, and can not argue regarding RAW, plus the tweet.

But in your opinion, does it seem reasonable that an eldritch knight can cast 2 non 0 spells/turn but a sorcerer can not unless he multiclasses to a fighter?

He can't?


On your turn, you can take one additional action on top of your regular action and a possible bonus action.

It's still on one turn.


You can’t cast another spell during the same turn, except for a cantrip with a casting time of 1 action.

So he has 2 actions and a bonus action. The Eldritch Knight or Fighter/Wizard can use one of them to cast one spell. That's it.

[Theodoxus]

I don't think the item should exist, period.

The rules are intended to limit the burst of spells. People who take 2 fighter make a significant sacrifice to do so. I would also not allow a magic item to allow you to have multiple concentration spells going at one.
Both of these break core limits on spellcasting.

On one hand, I agree. On the other, isn't it the purpose of magic items to break core limits? Certainly adding +1 to Hit breaks the Proficiency limit... so why is one considered 'good' and the other 'bad'?

Especially if the magic item was 1) only for spells - so fighters aren't slighted by having a magic item that just grants Action Surge and 2) recharged on a long rest - which again devalues the ability compared to fighters. Although, I'd probably make it a wand with 4 charges, recharge 1d3 per day, burn out on an 8 on a d8. That still puts it on par with a fighter short rest routine, but for spells only, with a chance of disappearing...


Now, as for Yoroichi's question as to fluffrgumentative reasons that Action Surge works for fighters, but not sorcerers... IDK. I'd say it has something to do with fighters being able to push the limits of man and beast and do incredible things, once an hour... but sorcerers are likewise proficient in Constitution saves, so could be argued to be just as robust (could definitely make the argument that wizards aren't - but sorcerers? ehh...)
So it would probably instead have to be something regarding their training, rather than their physical makeup.

I'd hazard to say that it's only because of EK that Action Surge even works on spells; I don't think anyone would have an issue if a DM decided that it only works with Fighter actions - though at that point, it might be best to just not use multiclassing; in which case, a magic item that replicates Action Surge becomes more viable - it's certainly no worse than a barbarian getting an item that allows him to fly or dimension door a few times a day.

[Yoroichi]

He can't?



It's still on one turn.



So he has 2 actions and a bonus action. The Eldritch Knight or Fighter/Wizard can use one of them to cast one spell. That's it.

yes obviously, but official tweet says otherwise...

[strangebloke]

I can see the fluff for a fighter/sorceror being better a quick casting than a lone sorcerer would.

Think of it like a warmage. He just isn't as good at casting spells as other magical people, but due to his intense physical training, he can sling out spells more quickly, even if they're weaker spells overall.

Sort of like somebody who is really good at speed chess, but most chess purists will look down upon because he isn't actually the best chess player.

[Kryx]

On one hand, I agree. On the other, isn't it the purpose of magic items to break core limits? Certainly adding +1 to Hit breaks the Proficiency limit... so why is one considered 'good' and the other 'bad'?

Especially if the magic item was 1) only for spells - so fighters aren't slighted by having a magic item that just grants Action Surge and 2) recharged on a long rest - which again devalues the ability compared to fighters. Although, I'd probably make it a wand with 4 charges, recharge 1d3 per day, burn out on an 8 on a d8. That still puts it on par with a fighter short rest routine, but for spells only, with a chance of disappearing...

The issue with breaking core limits on spells is that they are the one thing that allows other classes to compete. If they are removed then other classes fall behind and we return to the caster/martial divide of ol'. It exists still, but is heavily minimized.

[Theodoxus]

I don't see it that way, but I'll agree to disagree. The only time I can reasonably think that the need arises to cast two spells in a single round, is during combat.

There are very few times when you are going to need two spells in combat to not be blasts. Thanks to the Concentration rules, you're not going to Web/Hold/whatever CC, two times in one turn. CC then Blast is suboptimal as it typically breaks. Blast then CC works better (especially if it's an AOE followed by Sleep) but again, do you want to waste a very limited resource (Action Surge) on that?

Double nukes is where casters take front stage. Two 8d6 Fireballs back to back can be devastating to a pack of mooks. But again, this isn't an every combat kind of situation (unless you're drawing down short rests after every encounter). EKs will get it eventually, having access to Fireball - not as soon as F2/WizX, but eventually.

Even with blasting being not as suboptimal in 5th as it was in previous editions, its still not all that great. Bringing Fighters and Wizards to the same direct damage level isn't hard nor broken, from my experience. But again, I'm happy to concede that my experience might not be typical.

[Kryx]

I'm thoroughly confused.. My response was to the magic item you suggested which lets you overcome the 1 spell/turn rule. But then you talked about the fighter and action surge.

Action surge is fine as it comes at a cost.

I was arguing against giving action surge on a magic item.

[MeeposFire]

Action surge does not work for this.

The tweet is correct action surge actions can do anything that an action can do.

Unfortunately casting an action spell after a bonus action spell is NOT something that an action can do.

An action can allow you to cast two spells of any sort so long as you don't cast a bonus action spell.

Action surge allows you an extra action for free that follows all rules for actions of which this is just one.

The one possible exception I can see is if you go the odd route of being pedantic and follow the rules very literally which means so long as you use your action spell (and possibly action surge as well if you have it) before you cast your bonus action spells it works, but I do not recommend that route since it makes the rule functionally useless.

[Oscredwin]

Fighters are the master of getting **** done in combat. They can attack with a weapon more often than any other character, plus they have action surge. For me, it makes total sense that an EK can cast two full spells a turn with Action Surge. I would say they cast spells faster and with less extraneous movements than any other caster.

[Shadow]

Action surge does not work for this.

The tweet is correct action surge actions can do anything that an action can do.

Unfortunately casting an action spell after a bonus action spell is NOT something that an action can do.

An action can allow you to cast two spells of any sort so long as you don't cast a bonus action spell.

Action surge allows you an extra action for free that follows all rules for actions of which this is just one.

Incorrect.
The general rule is that you can only cast one spell as a bonus action and one cantrip as an action.
That's a general rule.
Action Surge is a specific rule. Specific trumps general.

[MeeposFire]

Fighters are the master of getting **** done in combat. They can attack with a weapon more often than any other character, plus they have action surge. For me, it makes total sense that an EK can cast two full spells a turn with Action Surge. I would say they cast spells faster and with less extraneous movements than any other caster.

Of course they can cast two action spells they can. Just not after a bonus action spell. They could cast two cantrips and a bonus action spell or two action based spells and no bonus action spell. IT is not a problem of skill it is a problem of that being a fundamental rule of magic

Heck that is probably a big part on why EKs use weapon attacks with their bonus action so that if you really want to blast something you could cast two spells and use your bonus action to stab it as well.

[MeeposFire]

Incorrect.
The general rule is that you can only cast one spell as a bonus action and one cantrip as an action.
That's a general rule.
Action Surge is a specific rule. Specific trumps general.

It would if it specifically say it does that. It lack any such language. All it gives you is an action. So no it is not specific to this instance.

Show me where it says that an action surge action is different from any other action. It says it is an action so just as the tweet says you need to treat it as any other action.

Why are you ignoring Crawford's tweet? You normally put so much faith in him. He said this "Yes, Action Surge can be used to do anything an action can normally do" but casting a non-cantrip after a bonus action spell is not something that an action can do. So are you going to listen to his tweet or are you going to ignore him and keep adding unlisted abilities to the action given from the action surge ability?

[Shadow]

Casting a spell is something that an action can do.
Action Surge does indeed have language making it specific.
"Starting at 2nd level, you can push yourself beyond your normal limitations for a moment. On your turn, you can take one additional action on top of your regular action and a possible bonus action."
Push yourself beyond your normal limitations.
Bonus action spell allowing no other spells except a cantrip is a normal limitation.
You ignore that limitation, and get one extra action, and that action can be anything that can normally be done in one action.
Casting a spell can normally be done in one action, so it is allowed.

edit:
You're apparently reading it as if he said "can be anything that a normal action can be during that round."
But that isn't what he said. He said anything that a normal action can be.
You're adding words to his response, when those words aren't present.
I'm following exactly what the tweet said. You're the one ignoring the tweet by putting words in his mouth.

You're placing the limitation on the action and claiming that this is what disqualifies it, but that isn't so.
The limitation is placed on your choices. Action Surge opens that choice back up again, because you "push yourself beyond your normal limitations."

[MeeposFire]

Casting a spell is something that an action can do.
Action Surge does indeed have language making it specific.
"Starting at 2nd level, you can push yourself beyond your normal limitations for a moment. On your turn, you can take one additional action on top of your regular action and a possible bonus action."
Push yourself beyond your normal limitations.
Bonus action spell allowing no other spells except a cantrip is a normal limitation.
You ignore that limitation, and get one extra action, and that action can be anything that can normally be done in one action.
Casting a spell can normally be done in one action, so it is allowed.

edit:
You're apparently reading it as if he said "can be anything that a normal action can be during that round."
But that isn't what he said. He said anything that a normal action can be.
You're adding words to his response, when those words aren't present.
I'm following exactly what the tweet said. You're the one ignoring the tweet by putting words in his mouth.

You're placing the limitation on the action and claiming that this is what disqualifies it, but that isn't so.
The limitation is placed on your choices. Action Surge opens that choice back up again, because you "push yourself beyond your normal limitations."

The way I am reading it the wording of the ability specifically calls out that it allows you an extra action. That alone is certainly breaking limitations. The way I see it this ability breaks limits on how many actions you can take in a round but not on how the actions can be used. 99% of the time there is no problem this is one of the few times where something prevents certain ways of using your action. To me this would also include anything else that would limit how your actions could be used such as you being stunned , restrained, etc (common english not necessarily the game terms) where even action surge can't allow you to do certain things. To me this still follows the tweet and the ability because it is exactly the same as the normal action no more, no less.

Thank you for at least trying to meet me halfway by using an actual rules quote. I don't agree with how you read it but I at least can see how you contort it (in my mind of course you would not see it that way and you would see my view similarly) to your view.


I think one piece of common ground for us is that I would think we can agree that the actual rule for bonus action spells is poorly worded currently. Right now technically it is useless as so long as you cast the action spells first you can freely cast bonus action spells afterword (few probably play it that way but it is there if you want to play by a strict reading). In addition the rule punishes you for choosing to use a bonus action cantrip rather than a bonus action spell. For instance if you cast a bonus action cantrip (say shillelagh) you have to cast another cantrip but if you cast a bonus action non-cantrip you also have to cast a cantrip. That seems odd that if you cast the bonus action as a cantrip that you can't cast a higher level spell but you could if you do it the other way around.

My solution would be in my games to change the rule to read like this...

In any round where you cast a bonus action spell and one or more other spells at least one of the spells cast (bonus or otherwise) must be a cantrip.

As far as I can tell allows free use of action surge as we all like it and allows you to cast your bonus action spell as a cantrip without putting yourself behind arbitrarily. This also follows more what people tend to think the rules say anyway.

[Yoroichi]

I am with Meeposfire on this, as i stated before. I couldn't phrase it correctly so i failed to present a proper counter argument.

In my view the spellcasting limitation is a world rule (cosmic order, law of the 5E universe), not a personal limit. When you use action surge you push yourself above the normal and you can take an extra action as a result. You can not break the rules of magic that apply to the whole 5E universe. Specific does beat general, but in this instant, in my opinion for action surge to work as shadow proposes, it would need to be specified in the wording.

[Dalebert]

It says he can push beyond his normal limitations. Then it explains exactly how--by taking an extra action. Normally characters get one action so that is clearly beyond normal limitations. It doesn't say it does anything more. It certainly doesn't say the fighter is free from normal spell restrictions. The spell restriction isn't per action. If it was, I would agree with you. The restriction is per turn. The fighter isn't get an extra turn. He's getting two actions within his one turn.

Normal turn: 1 move, 1 action, 1 bonus action

Fighter action surge turn: 1 move, 2 actions, 1 bonus action

By the twisted logic you're using, you could pick any restriction in the game on an action and say the fighter isn't restricted by it, e.g. "TWF says you don't get your ability bonus on the damage of the 2nd weapon attack, but the fighter is pushing himself past his normal limitations with action surge so he still gets it." Uh... nope..

Like was said, the restriction is on bonus action spells so he can still cast two spells if they are both normal action spells. That's quite powerful.