Overchannel. By RAW, it works as long as the spell lasts. Not exactly the intent (works only on the first turn), but it's functional. #DnD https://t.co/5ibPHCypsJ
— Jeremy Crawford (@JeremyECrawford) November 14, 2016
@quadhund so “When you cast a … spell” wording applies abilities to spell for duration? Bigby’s language implies otherwise 1/2 I ruled on the wording of Overchannel (an exception). The wording of an exception has no bearing on the general rules.
— Jeremy Crawford (@JeremyECrawford) November 15, 2016