Split Casting and Boosting Charisma

[subject42]

As a DM, I have gotten a bit tired of all non-spontaneous casters dumping Charisma. While it's unfortunate, it makes sense, given that Charisma isn't used for much outside of a small number of skills and class features. If possible, I'd like to boost Charisma by making it have a more universal application.

Assuming a new campaign, how disruptive would the following house rule be?

All characters with a casting progression use their current primary casting ability score for the purpose of determining the number of spells per day that they may cast, as well as the number of bonus spells per day that they may cast.

The save DC of a spell is determined by the character's charisma modifier.

This indirectly boosts the relative power of Charisma-based casters, as well.

[Douglas]

Charisma isn't used for much outside of a small number of skills and class features.

Small? SMALL???

Take a look in this thread and click to show the spoiler for charisma. That is far from a small list, and the sheer number and availability of things in that list actually makes charisma the single most important ability score in a lot of optimization just because you can get it applied to so many things so many times so easily.

Now if you're talking about non optimized characters with simple builds that's another matter, but in that case why are you approaching this from a rules mechanical perspective?

[Devils_Advocate]

My guess is that making casters more SAD would generally make them a bit less uber, and I think that Cha-based casters tend to be relatively underpowered, so I think that it would probably improve game balance.

Making spells harder to resist based on the caster's "force of personality" makes a fair bit of sense, too, although making one stat universal across spellcasting classes like that changes the general flavor of magic a bit.

Thinking about it, I think that it might make sense to base save DCs on Cha, spells per day on Wis, and known spells on Int. But that might be a better idea for one generic spellcasting class than as an adjustment to all of the existing classes.

[jiriku]

You could always, you know, emphasize social interaction in your games. Players optimize Str or Int because they expect to fail important rolls if they don't. If low Cha starts causing them to fail important rolls, they'll probably begin to put more emphasis on it.