How does the grave domain Circle of Mortality feature work with the Life Transference spell on a 0 HP target?

@JeremyECrawford how does the grave domain Circle of Mortality feature work with the Life Transference spell on a 0 hp target? Full damage taken by the caster?

— Zoey Proasheck (@Proasheck) November 16, 2017

In life transference, you roll damage, not healing. Healing is a consequence of the damage. #DnD https://t.co/jt2rPj2AO8

— Jeremy Crawford (@JeremyECrawford) November 16, 2017