Energy Drain

Drains hit points equal to hit dice.
You fire a ray of necrotic energy at the target. If it fails a Constitution save, it loses hit points equal to the maximum number of its hit dice multiplied by 1D6 and the caster gains temporary hit points equal to half the result. If it succeeds, divide the end result in half and the caster does not gain temporary hit points. If the target's hit points is reduced to 0 from this spell, the target dies. These hit points can only be restored at the end of a long rest or by the effect of a Greater Restoration spell.