When casting Chaos Bolt and using the Empowered Spell metamagic on the first damage roll, would you be able to reroll only up to the first two d8s, or would you be able to reroll potential secondary damage dice too assuming your charisma modifier was high enough? You can reroll as many dice as your Charisma modifier allows.

— Jeremy Crawford (@JeremyECrawford) December 22, 2017