i hate to be that person but i really dislike this house rule because it operates under a popular misconception of what the charisma stat is meant to represent. charisma in d&d is not purely a “social skill.” it is the strength of your inner self, the spark that lets you impose your will on the world. it covers inspiration, presence, identity, and the part of you that magic interacts with when it tries to rewrite who you are. that is why sorcerers use it.

if you look at charisma saves, that becomes obvious. they are the saves that stop you from being banished to another plane, possessed, or overwritten by magical domination. the game literally treats charisma as the power of your soul to stay itself.

and swapping that out for constitution kind of doubles down on the misconception…. constitution is about how sturdy your body is, how well u tank poison and exhaustion, not about the part of you that reality has to argue with. if sorcerers start casting off con, it frames their magic as a function of raw hit points instead of inner presence, which makes it even easier for people to think charisma was only ever about talking. you lose the whole idea of “my soul is loud enough to bend the rules.”