Erratic Concentration

Whenever you cast a spell that would ordinarily require concentration, make an Intelligence saving throw, using your Charisma ability score as the DC.

If this initial saving throw is successful, the spell lasts for its entire duration without the need for concentration. It can only be terminated early by using an action, and only upon a successful intelligence saving throw (DC is your Charisma ability score plus your Proficiency Bonus).

If the initial saving throw is unsuccessful, the spell is automatically dismissed as if concentration broke at the end of the your current turn (or, if the spell was not cast on the your turn, at the end of your next turn). In the round following the dismissal of the spell, you can take an additional Reaction.

Author's Note: This feat was inspired by my own experience with ADHD. While it always confers a benefit, that benefit is intentionally unpredictable. Version 2 simplifies the DCs for intelligence saves and adds a related prerequisite.