Arcane Siphon

You cast this spell on a target and every spell that they cast you instead get the opportunity to cast their spell instead of them. The target must make a charisma saving throw against you spell save DC. On a failure they are unaware that the spell has been cast on them and every spell that they cast you have the opportunity to cast that spell instead. You choose before they cast the spell if you want to cast the spell instead of them. The target thinks that their spell either missed or didn't work. On a success, the target is aware that this spell was attempted on them and the spell doesn't work.