Unweave

You crush the ashen brain in your hand, which opens somehow cleaner than before. One creature you can see and hear within range makes a saving throw using its spell casting ability. If it fails, it makes another such saving throw at the end of its next turn. If it fails again, it loses the ability to cast spells from any source forever.

This ability can only be restored if another creature uses Divine Intervention or casts wish to restore it, in which case the unwoven creature gets a new saving throw and regains its magic if it succeeds. If the target has no existing spellcasting abilities, it automatically fails all saving throws associated with this spell.