Spellcasting Convergence: A feat for MAD multiclass casters

[Ettina]

Spellcasting Convergence
Prerequisite: At least one level in two or more classes with the Spellcasting or Pact Magic feature that use different spellcasting ability scores

You synchronize your spellcasting abilities to all draw upon a single spellcasting ability. You gain the following benefits:

* Increase your Intelligence, Wisdom, or Charisma score by 1, to a maximum of 20. The ability score you increase must be a spellcasting ability score for at least one of your classes.
* All spells you can cast use the score you increased for this feat as your spellcasting ability score.

[supercereal]

No

[noob]

The main reason to avoid multiclassing between spell casting classes is not casting stats: it is the issue of reducing maximal spell known level.

[GentlemanVoodoo]

This seems like it should be more as perhaps a boon type reward earned in game. To allow something like this does bring up to much balancing issues to my mind, taking into consideration other things like class features which may impact the spell as to the spell itself.

Though one alternative might be to work it as allowing a player to select one spell from which they have class levels in that does not use the stat of which the increase was applied to and allow them to cast the spell with the stat in question as a once per long rest use. Maybe allow them to switch out the spell when they prepare spells is a possible option as well.

But again I see something like this being some kind of boon or magic item the player earns in game.