You are hit by a Specter’s Life Drain for 10 damage. You have 8 temporary hit points. Is your Max HP lowered by 2 or by 10?

You are hit by a Specter’s Life Drain for 10 damage. You have 8 temporary hit points. Is your Max HP lowered by 2 or by 10? By 10

— Jeremy Crawford (@JeremyECrawford) January 15, 2018