Unwilling Novice

You send a creature’s memories backwards in time, causing familiar notions to suddenly appear foreign. The target must make a Wisdom saving throw. On a failure, the target can't add its proficiency bonus to its attack rolls, ability checks, and saving throws for the duration.

At the end of each of its turns, the target can make another Wisdom saving throw. On a success, the spell ends on the target. If the spell ends before 1 minute has passed, nothing happens. Otherwise, you permanently remove one of the target's proficiencies, choosing between its armor, weapon, tool, and skill proficiencies.