At level 1: Constitution is your spell casting ability for your sorcerer spells, since the power of your magic is inherent to you.
At level 2: Font of Magic. You gain a number of sorcery points equal to your Sorcerer level + half your charisma modifier rounded up.
At level 3: Meta Magic. You can select a number of Meta magic options equal to your Charisma modifier (minimum of 1).
At 10th level: Your Sorcery Points equal your level + your Charisma modifier.
At 17th level: A 1st level Spell Slot now costs only 1 Sorcery Point.
Multi-Classing: You must have atleast a 13 in both Charisma and Constitution. .................................................. .........................
The Mechanical Argument:
The Sorcerer is functionally a less complicated Wizard. I believe it is intended to be the easiest spell caster and inviting to new players. The above alterations do not change that. In WotC efforts to make Sorcerers more accessible, they have given the Sorcerer less options. This is ok, but I'd we are going to give a class less options we should allow them to do more with those options.
WHY CAST WITH CONSTITUTION? Firstly, to make the class distinctive from other casters. Sorcerers should be THE concentration spell caster, they are the best as maintaining their spells in the heat of battle. Unlike Wizards, Sorcerers and their Hitpoint bonus from Con, can be front and center in combat casting close range AOEs. This would be the arcane answer to the Cleric. The trade off is that without a proficiency in armor, most Sorcerers are going to be hit more often. They would play very differently than other casters, and those extra hitpoints will be more forgiving to a new player, who are the target demographic for this class.
WHY THE EXTRA SORCERY POINTS AND WHY TIE IT TO CHARISMA? Mostly to insensitiveize players to not just put everything into Constitution. The added benefit is that low level Sorcerers get to interact with what makes their class special more often. The highest a Sorcerer's Charisma modifier can be at level two, is 4. This would give them a total of 6 Sorcery Points, or 3 extra 1st level spell slots. This seems like alot, but next level they will be spending SP on meta magic and an equilibrium will be reached. Since alot of Sorcerer spells are concentration (and I believe more concentration spells should be added to their spell list), these extra spell slots can incentivize a Sorcerer to drop one concentration spell for another.
WHY THE CHANGE TO META MAGIC OPTIONS? Again, to incentivize players to put points in something other than Constitution. This also gives a player more opportunities to experiment with different meta magic and reduces the chance that they regret their choices.
WHY THE MULTI-CLASS RESTRICTIONS? Requiring both Constitution and Charisma prevents everyone from being able to dip into Sorcerer with out making sacrifices. .................................................. .........................
The Thematic Argument:
I understand that Charisma is also the "Willpower" stat, but I disagree that a Sorcerer's power comes from their will. Magic is like an organ to the Sorcerer, it is part of them. They are their own battery. A Sorcerer's will can be used to shape and modify their magic, that is why Charisma is tied to SP and MM. The reason Constitution is their spell casting ability is because it reflects their ability to contain and control their magic. A creature with low Constitution would be consumed by the raw magical power infused within them.
NOW THE MOST THEMATIC RACES NO LONGER SYNERGIZE WITH THE CLASS!
The nature of Sorcery, as opposed to Wizardry, is that it is random. Why are Halflings, Half-Elves, and Dragonborn more likely to be Sorcerers? There is no reason they should be, and Stout Halflings and Half-Elves still are even if there was. An argument could be made for Tiefling and Aasimar, but they still benefit from better than average MM and SP.
AND NOW LESS THEMATIC RACES SYNERGIZE BETTER WITH THE CLASS!!
This makes perfect sense. A race that does not have many magic users would quickly be outpaced by those who do. While Orcs may not have the capacity to train wizards, they can rely on their Sorcerers to fill that niche. The study of magic would take time away form the study of more practical arts in the eyes of Dwarves, but those with innate magic would still be valued by the Dwarven community. It would make since that these races would have more Sorcerers than other types of magic users. Dragonborn and Genasi already cast innate magic using Constitution, so this isn't a revolutionary idea. .................................................. .........................
The Sorcerer as written is a fine class with great flavor, but other spell casting classes out pace in almost every way. It also doesn't play much differently than a Wizard. In the end its just a mechanically worse version of the Wizard. These subtle changes make the Sorcerer a very different experience and enable unique character builds and playstyles.
So what do you think? Is this good, is this terrible? I've had this debate many times, and I think I've refined it and balanced it so that most should find it acceptable.
One problem with Con casters is that they'd be very strong. By being able to put everything into Con, a caster would have a good casting stat, good HP and good saves for concentration spells. Concentration spells are usually on the upper end of the power curve, so being able to double dip Con for hp/saves and spellcasting ability would be very, very strong.
Interesting idea. Potentially extremely powerful, as Dave mentioned, but the other thing this would do would be to break the unholy cancer tumor of Charisma Multiclassing, where half the gorram classes in the game all compound in ways that make everyone else kinda hate Charisma casters.
I'd honestly be curious to see what a playtest of the idea said. If clerics, druids and rangers are allowed to Double Up(C) on a primary saving throw also being their casting stat, and finesse/ranged attackers are allowed to Double Up(C) on a primary saving throw also being their attacking stat, I wonder if allowing one spellcaster in the game to Double Up(C) on the last primary saving throw would really break things that hard. Not like everyone in the game doesn't already tank the hell out of their non-save stats as it is unless their class demands otherwise, the munchkinning is real. Why not see what happens when we break up the Gordian Charisma Knot a little bit?
True, but they are still susceptible to focus fire, and they are going to be relatively easy to hit even if they put points in dexterity. If they decide to put everything into Constitution and not charisma then they are sacrificing variability in favor of doing the one thing they do very well, a fair trade in my opinion.
Requiring cha and con for multiclass is not a barrier to entry that would affect people dipping sorc. Not many people dump con. Are pally, bard and to extent warlocks dumping con? I doubt it.
You mention no armor being a barrier. Dragon sorcerers have that covered and others can solve it with any number of 1 level dips.
It just feels like a having your cake and eating it too situation.
Keep in mind that Multi-classing is an optional rule, you don't have to let your players do it. In my games I tell my players they can't multi-class until level 6 and they must have a narrative justification. It's really hard to justify a Sorcerer dip, you can't train to be a Sorcerer.
I'm not trying to make Sorcerers "better" I'm trying to make more variations of playstyles. The Draconics will be really good choices for people that want to mix it up on the front line, but they are going to have to spend points in Dexterity to make it viable. If a Sorcerer gains access to Heavy Armor somehow they are going to have to spend points into Strength to wear it. I can't imagine this is to be worse than the Paladin/Warlock.
Interesting idea. //SNIP!// this would do would be to break the unholy cancer tumor of Charisma Multiclassing, where half the gorram classes in the game all compound in ways that make everyone else kinda hate Charisma casters.
Count me as one of the people that hate the plethora of CHA based casters. Bards are fine, but adding Warlocks and Bards into the mix as well makes CHA equal to DEX as a power stat and that is undesirable in a game design.
Interesting idea. Potentially extremely powerful, as Dave mentioned, but the other thing this would do would be to break the unholy cancer tumor of Charisma Multiclassing, where half the gorram classes in the game all compound in ways that make everyone else kinda hate Charisma casters.
Interesting idea. //SNIP!// this would do would be to break the unholy cancer tumor of Charisma Multiclassing, where half the gorram classes in the game all compound in ways that make everyone else kinda hate Charisma casters.
Count me as one of the people that hate the plethora of CHA based casters. Bards are fine, but adding Warlocks and Bards into the mix as well makes CHA equal to DEX as a power stat and that is undesirable in a game design.
I agree! I’d love to see Sorcerers changed to Constitution based casters without changing anything else about them and Warlock’s changed to Intelligence based casters without changing anything else about them. Not only for balance reasons when multiclassing, but for thematic reasons too. Those two classes just feel better being based on stats other than Charisma.
Keep in mind that Multi-classing is an optional rule, you don't have to let your players do it. In my games I tell my players they can't multi-class until level 6 and they must have a narrative justification. It's really hard to justify a Sorcerer dip, you can't train to be a Sorcerer.
Nothing says powers are active from birth. Dormant powers awakened later in life. There are genes in real life that can activate later in life, seems easy to accept fantasy powers doing so. Not sure why that would be hard to justify?
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The rest I have no stamina to bother discussing again. Already done so in multipleotherthreads and seen nothing yet to change my opinion on the matter (it should stay Cha).
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I can see maybe a subclass working as they get that option at level one, but it would have to tag something onto the spells like taking damage when casting, maybe 2 x spell level.
Or a way to restore sorcery points with health.
It would have to be something juicy enough to make players want to use the feature and not just pick that subclass for the less MAD set up.
It's not a bad idea, IMO. There is a narrative reason for it as well as a mechanical one. I wonder if it would make the War Wizard subclass a bit redundant, though. Worth playtesting to find out. I do also like the idea of reducing S.P. cost of 1st level spells at 17th level.
It's hard to keep track of every little update to the game lore with each edition, but...
I don't agree with Sorcerers using Constitution for spells because Charisma just works better. Charisma reflects several qualities, but notably, "inner-strength" and "force of will", which is pretty easy to pin point as the roots of a Sorcerer's power for me.
That said, I would be happy to see a Sorcerer (or any class I guess) subclass that utilized metamagic (or similar) by sacrificing Hit Dice and drawing on Constitution as their spellcasting source. I think this was the general idea behind Matt Mercer's class, but it isn't really a spellcasting class.
With the current game lore, all of the caster's primary attributes make sense, although I do miss Bards having spell books and using Intelligence. I also think Paladins work fine with either Wisdom or Charisma. Warlocks make sense as being Intelligence casters since they're frequently researching the dark secrets of their power, but that argument falls apart the minute you introduce the patron.
I don't agree with Sorcerers using Constitution for spells because Charisma just works better. Charisma reflects several qualities, but notably, "inner-strength" and "force of will", Warlocks make sense as being Intelligence casters since they're frequently researching the dark secrets of their power, but that argument falls apart the minute you introduce the patron.
Well maybe but you can always have them researching the documentation given to them by the Patron, not explicit in the rule but it's a different way of thinking about it if you wanted an Int warlock
I agree with Davedaemon, making a caster class con based is way too powerfull. There's a reason con is not a primary stat for any class and it's because it's almost always your secondary stat. Mechanically, it would just plain unbalance the class, not that the classes are balanced as it is 😉
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Everyone here acting like there's a +5 disparity between your primary and secondary stat. A sorcerer already can get all these benefits by not dumping CON. If a player dumps CHA because it's not required for their spells anymore, the game will punish them for that. They're going to be completely ineffective in roleplaying negotiations, intimidations, or misinformation. Even if they prioritize con, they're still going to want to maintain other stats and it's not going to manifest in obscene numbers without making sacrifices somewhere else that you can easily punish.
Constitution is already a very powerful ability score. There's absolutely no reason to make it stronger. Also, casting spells via constitution doesn't make sense.
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"Canon" is what's factual to D&D lore. "Cannon" is what you're going to be shot with if you keep getting the word wrong.
I have to agree with some of those that have already posted, CON should NOT be the primary stat for a spellcaster. Most spellcasters use CON as their second highest stat already, making it their primary stat would be too powerful.
CON controls HP and concentration saves, making it the spellcasting stat as well would be a mistake IMHO.
There's a reason no class uses CON as its primary ability, and it should stay that way. Doing so would mean that HP, attack, and damage modifiers would all be keyed to the same ability score (and in the case of spellcasters, concentration rolls as well).
Con represents bodily fortitude, spellcasting should always be tied to a mental stat.
As far as the problem of multi-classing CHA - based classes, I agree - but that can be mitigated by the DM. Take Warlocks for example. Why would a patron agree to a pact if the character only plans on a one level dip into the class? If someone wants to play a Warlock, the DM should have them negotiate a pact. What exactly will they be providing the patron in exchange for the arcane knowledge (they are not going to give it away for free). If a DM allows multi-classing to be used for one level 'dips' then they deserve the munchkins that they get. If someone can't come up with a good story-related reason for it (that fits the campaign), don't allow them to do it. Just because someone wants to pick up a level in a class, doesn't mean they'll find someone willing to teach them.
Look at Paladin/Warlocks for example. Not many deities would allow a Paladin to enter into a Pact with another deity or extra-planar being of power unless an ally or subordinate of that deity. I had one player who had a Paladin of a lawful good deity who wanted to multi-class into warlock to become a hexblade. Not only did I point out that the only being in my campaign able to grant hexblade abilities would conflict with their chosen deity, but when I asked why the character even wanted to pursue it, they answered, "because the character lost an important fight, obviously their god isn't strong enough to protect them, so he needs to make a pact with someone who is." I told him that if that's his character's reasoning, then his deity is going to have issues with his waivering faith - he won't be able to pursue both of those paths.
The statement of "just because you can, does not mean you should." Is a major factor in the argument. That statement and all of the reasoning why you should make con a single stat reminds me of ethics. To go against Ethics aka be unethical has nothing to do with something being legal. It has everything to do with doing what is the "correct" thing to do. Every reason people use to make Con a spellcaster ability would be "legal". But all of the reasons to not allow it, fall under the reasons of being correct/ethical/right/etc.
Keep in mind that Multi-classing is an optional rule, you don't have to let your players do it. In my games I tell my players they can't multi-class until level 6 and they must have a narrative justification. It's really hard to justify a Sorcerer dip, you can't train to be a Sorcerer.
I'm not trying to make Sorcerers "better" I'm trying to make more variations of playstyles. The Draconics will be really good choices for people that want to mix it up on the front line, but they are going to have to spend points in Dexterity to make it viable. If a Sorcerer gains access to Heavy Armor somehow they are going to have to spend points into Strength to wear it. I can't imagine this is to be worse than the Paladin/Warlock.
I would forward the idea that Sorcerer is the easiest class to justify multi-classing into. Literature is rife with characters suddenly coming into their powers unexpectedly.
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First what we would Change:
At level 1: Constitution is your spell casting ability for your sorcerer spells, since the power of your magic is inherent to you.
At level 2: Font of Magic. You gain a number of sorcery points equal to your Sorcerer level + half your charisma modifier rounded up.
At level 3: Meta Magic. You can select a number of Meta magic options equal to your Charisma modifier (minimum of 1).
At 10th level: Your Sorcery Points equal your level + your Charisma modifier.
At 17th level: A 1st level Spell Slot now costs only 1 Sorcery Point.
Multi-Classing: You must have atleast a 13 in both Charisma and Constitution.
.................................................. .........................
The Mechanical Argument:
The Sorcerer is functionally a less complicated Wizard. I believe it is intended to be the easiest spell caster and inviting to new players. The above alterations do not change that. In WotC efforts to make Sorcerers more accessible, they have given the Sorcerer less options. This is ok, but I'd we are going to give a class less options we should allow them to do more with those options.
WHY CAST WITH CONSTITUTION?
Firstly, to make the class distinctive from other casters. Sorcerers should be THE concentration spell caster, they are the best as maintaining their spells in the heat of battle. Unlike Wizards, Sorcerers and their Hitpoint bonus from Con, can be front and center in combat casting close range AOEs. This would be the arcane answer to the Cleric. The trade off is that without a proficiency in armor, most Sorcerers are going to be hit more often. They would play very differently than other casters, and those extra hitpoints will be more forgiving to a new player, who are the target demographic for this class.
WHY THE EXTRA SORCERY POINTS AND WHY TIE IT TO CHARISMA?
Mostly to insensitiveize players to not just put everything into Constitution. The added benefit is that low level Sorcerers get to interact with what makes their class special more often. The highest a Sorcerer's Charisma modifier can be at level two, is 4. This would give them a total of 6 Sorcery Points, or 3 extra 1st level spell slots. This seems like alot, but next level they will be spending SP on meta magic and an equilibrium will be reached. Since alot of Sorcerer spells are concentration (and I believe more concentration spells should be added to their spell list), these extra spell slots can incentivize a Sorcerer to drop one concentration spell for another.
WHY THE CHANGE TO META MAGIC OPTIONS?
Again, to incentivize players to put points in something other than Constitution. This also gives a player more opportunities to experiment with different meta magic and reduces the chance that they regret their choices.
WHY THE MULTI-CLASS RESTRICTIONS?
Requiring both Constitution and Charisma prevents everyone from being able to dip into Sorcerer with out making sacrifices.
.................................................. .........................
The Thematic Argument:
I understand that Charisma is also the "Willpower" stat, but I disagree that a Sorcerer's power comes from their will. Magic is like an organ to the Sorcerer, it is part of them. They are their own battery. A Sorcerer's will can be used to shape and modify their magic, that is why Charisma is tied to SP and MM. The reason Constitution is their spell casting ability is because it reflects their ability to contain and control their magic. A creature with low Constitution would be consumed by the raw magical power infused within them.
NOW THE MOST THEMATIC RACES NO LONGER SYNERGIZE WITH THE CLASS!
The nature of Sorcery, as opposed to Wizardry, is that it is random. Why are Halflings, Half-Elves, and Dragonborn more likely to be Sorcerers? There is no reason they should be, and Stout Halflings and Half-Elves still are even if there was. An argument could be made for Tiefling and Aasimar, but they still benefit from better than average MM and SP.
AND NOW LESS THEMATIC RACES SYNERGIZE BETTER WITH THE CLASS!!
This makes perfect sense. A race that does not have many magic users would quickly be outpaced by those who do. While Orcs may not have the capacity to train wizards, they can rely on their Sorcerers to fill that niche. The study of magic would take time away form the study of more practical arts in the eyes of Dwarves, but those with innate magic would still be valued by the Dwarven community. It would make since that these races would have more Sorcerers than other types of magic users. Dragonborn and Genasi already cast innate magic using Constitution, so this isn't a revolutionary idea.
.................................................. .........................
The Sorcerer as written is a fine class with great flavor, but other spell casting classes out pace in almost every way. It also doesn't play much differently than a Wizard. In the end its just a mechanically worse version of the Wizard. These subtle changes make the Sorcerer a very different experience and enable unique character builds and playstyles.
So what do you think? Is this good, is this terrible? I've had this debate many times, and I think I've refined it and balanced it so that most should find it acceptable.
One problem with Con casters is that they'd be very strong. By being able to put everything into Con, a caster would have a good casting stat, good HP and good saves for concentration spells. Concentration spells are usually on the upper end of the power curve, so being able to double dip Con for hp/saves and spellcasting ability would be very, very strong.
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Interesting idea. Potentially extremely powerful, as Dave mentioned, but the other thing this would do would be to break the unholy cancer tumor of Charisma Multiclassing, where half the gorram classes in the game all compound in ways that make everyone else kinda hate Charisma casters.
I'd honestly be curious to see what a playtest of the idea said. If clerics, druids and rangers are allowed to Double Up(C) on a primary saving throw also being their casting stat, and finesse/ranged attackers are allowed to Double Up(C) on a primary saving throw also being their attacking stat, I wonder if allowing one spellcaster in the game to Double Up(C) on the last primary saving throw would really break things that hard. Not like everyone in the game doesn't already tank the hell out of their non-save stats as it is unless their class demands otherwise, the munchkinning is real. Why not see what happens when we break up the Gordian Charisma Knot a little bit?
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True, but they are still susceptible to focus fire, and they are going to be relatively easy to hit even if they put points in dexterity. If they decide to put everything into Constitution and not charisma then they are sacrificing variability in favor of doing the one thing they do very well, a fair trade in my opinion.
Requiring cha and con for multiclass is not a barrier to entry that would affect people dipping sorc. Not many people dump con. Are pally, bard and to extent warlocks dumping con? I doubt it.
You mention no armor being a barrier. Dragon sorcerers have that covered and others can solve it with any number of 1 level dips.
It just feels like a having your cake and eating it too situation.
Keep in mind that Multi-classing is an optional rule, you don't have to let your players do it. In my games I tell my players they can't multi-class until level 6 and they must have a narrative justification. It's really hard to justify a Sorcerer dip, you can't train to be a Sorcerer.
I'm not trying to make Sorcerers "better" I'm trying to make more variations of playstyles. The Draconics will be really good choices for people that want to mix it up on the front line, but they are going to have to spend points in Dexterity to make it viable. If a Sorcerer gains access to Heavy Armor somehow they are going to have to spend points into Strength to wear it. I can't imagine this is to be worse than the Paladin/Warlock.
Count me as one of the people that hate the plethora of CHA based casters. Bards are fine, but adding Warlocks and Bards into the mix as well makes CHA equal to DEX as a power stat and that is undesirable in a game design.
I agree! I’d love to see Sorcerers changed to Constitution based casters without changing anything else about them and Warlock’s changed to Intelligence based casters without changing anything else about them. Not only for balance reasons when multiclassing, but for thematic reasons too. Those two classes just feel better being based on stats other than Charisma.
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Nothing says powers are active from birth. Dormant powers awakened later in life. There are genes in real life that can activate later in life, seems easy to accept fantasy powers doing so. Not sure why that would be hard to justify?
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The rest I have no stamina to bother discussing again. Already done so in multiple other threads and seen nothing yet to change my opinion on the matter (it should stay Cha).
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I can see maybe a subclass working as they get that option at level one, but it would have to tag something onto the spells like taking damage when casting, maybe 2 x spell level.
Or a way to restore sorcery points with health.
It would have to be something juicy enough to make players want to use the feature and not just pick that subclass for the less MAD set up.
It's not a bad idea, IMO. There is a narrative reason for it as well as a mechanical one. I wonder if it would make the War Wizard subclass a bit redundant, though. Worth playtesting to find out. I do also like the idea of reducing S.P. cost of 1st level spells at 17th level.
It's hard to keep track of every little update to the game lore with each edition, but...
I don't agree with Sorcerers using Constitution for spells because Charisma just works better. Charisma reflects several qualities, but notably, "inner-strength" and "force of will", which is pretty easy to pin point as the roots of a Sorcerer's power for me.
That said, I would be happy to see a Sorcerer (or any class I guess) subclass that utilized metamagic (or similar) by sacrificing Hit Dice and drawing on Constitution as their spellcasting source. I think this was the general idea behind Matt Mercer's class, but it isn't really a spellcasting class.
With the current game lore, all of the caster's primary attributes make sense, although I do miss Bards having spell books and using Intelligence. I also think Paladins work fine with either Wisdom or Charisma. Warlocks make sense as being Intelligence casters since they're frequently researching the dark secrets of their power, but that argument falls apart the minute you introduce the patron.
Well maybe but you can always have them researching the documentation given to them by the Patron, not explicit in the rule but it's a different way of thinking about it if you wanted an Int warlock
I agree with Davedaemon, making a caster class con based is way too powerfull. There's a reason con is not a primary stat for any class and it's because it's almost always your secondary stat. Mechanically, it would just plain unbalance the class, not that the classes are balanced as it is 😉
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Everyone here acting like there's a +5 disparity between your primary and secondary stat. A sorcerer already can get all these benefits by not dumping CON. If a player dumps CHA because it's not required for their spells anymore, the game will punish them for that. They're going to be completely ineffective in roleplaying negotiations, intimidations, or misinformation. Even if they prioritize con, they're still going to want to maintain other stats and it's not going to manifest in obscene numbers without making sacrifices somewhere else that you can easily punish.
Constitution is already a very powerful ability score. There's absolutely no reason to make it stronger. Also, casting spells via constitution doesn't make sense.
Find your own truth, choose your enemies carefully, and never deal with a dragon.
"Canon" is what's factual to D&D lore. "Cannon" is what you're going to be shot with if you keep getting the word wrong.
I have to agree with some of those that have already posted, CON should NOT be the primary stat for a spellcaster. Most spellcasters use CON as their second highest stat already, making it their primary stat would be too powerful.
CON controls HP and concentration saves, making it the spellcasting stat as well would be a mistake IMHO.
There's a reason no class uses CON as its primary ability, and it should stay that way. Doing so would mean that HP, attack, and damage modifiers would all be keyed to the same ability score (and in the case of spellcasters, concentration rolls as well).
Con represents bodily fortitude, spellcasting should always be tied to a mental stat.
As far as the problem of multi-classing CHA - based classes, I agree - but that can be mitigated by the DM. Take Warlocks for example. Why would a patron agree to a pact if the character only plans on a one level dip into the class? If someone wants to play a Warlock, the DM should have them negotiate a pact. What exactly will they be providing the patron in exchange for the arcane knowledge (they are not going to give it away for free). If a DM allows multi-classing to be used for one level 'dips' then they deserve the munchkins that they get. If someone can't come up with a good story-related reason for it (that fits the campaign), don't allow them to do it. Just because someone wants to pick up a level in a class, doesn't mean they'll find someone willing to teach them.
Look at Paladin/Warlocks for example. Not many deities would allow a Paladin to enter into a Pact with another deity or extra-planar being of power unless an ally or subordinate of that deity. I had one player who had a Paladin of a lawful good deity who wanted to multi-class into warlock to become a hexblade. Not only did I point out that the only being in my campaign able to grant hexblade abilities would conflict with their chosen deity, but when I asked why the character even wanted to pursue it, they answered, "because the character lost an important fight, obviously their god isn't strong enough to protect them, so he needs to make a pact with someone who is." I told him that if that's his character's reasoning, then his deity is going to have issues with his waivering faith - he won't be able to pursue both of those paths.
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The statement of "just because you can, does not mean you should." Is a major factor in the argument. That statement and all of the reasoning why you should make con a single stat reminds me of ethics. To go against Ethics aka be unethical has nothing to do with something being legal. It has everything to do with doing what is the "correct" thing to do. Every reason people use to make Con a spellcaster ability would be "legal". But all of the reasons to not allow it, fall under the reasons of being correct/ethical/right/etc.
I would forward the idea that Sorcerer is the easiest class to justify multi-classing into. Literature is rife with characters suddenly coming into their powers unexpectedly.