Quartz
Hero
Don't forget that you're forcing a creature to use its one and only reaction. And really, how often will a PC make a DC 25 CHA save? If they're proficient in CHA and have a high stat (bard, warlock, sorceror, paladin) they'll be saving at +9 to +11 at level 20, but that's rolling a 14 or more at best. A 2/3 chance of failure. And what about all the others? Your level 20 fighter or wizard or cleric or barbarian or... is going to be saving at maybe +1 or +2, so will only save on a 20.