Silvery barbs is a powerful spell, but not gamebreaking.
I find it's way too "much", and I would very much for it and its ilk to be removed from the game.
I mean, if a very specific build could get it, so you'd have a single character every third campaign use it, okay.
But the way "spend your reaction to force the enemy to miss or reroll" is way too intrusive in the game. Our Wizard had and used it. I found my Eldritch Trickster had nothing even close to its power with my otherwise feeble spellcasting. Our Rune Knight had his own variant.
It makes encounters too easy, since you can "nova" these powers. When you can force not just one but three re-rolls per round, that wins combats all by itself.
It makes encounters too slow, since you have introduced a decision point
after every enemy success. It's basically a shitshow when the player is prone to analysis paralysis.
Out of combat it has
WAY too much narrative power, when you use it to dramatically reduce the chance for a NPC to succeed at anything (a performance, diplomacy, intimidation, whatever).
So while "Silvery barbs is a powerful spell, but not gamebreaking." may be true technically, in practice, the game is better off without it.
Also, just because it might not be gamebreaking doesn't mean it's a well designed spell. It should definitely come with some form of power limit, so a 1st level slot isn't just as awesome at level 1 as on level 20. Basically, if you needed to spend a high level slot to influence a high level NPC, okay.
But you don't. You can be the crappiest spellcaster in the world and this spell works just as well on a kobold and a demigod.
TL;DR: Just because you can, doesn't mean you should.
I hope the new edition removes "spend your reaction to make monsters reroll" altogether.
