As a reaction when a creature is reduced to 0 hit points within 60 feet of you, you harness that creature's fading life energy, pulling at the essence that exists on the blurred line between life and death.  The creature's corpse explodes into a burst of ghastly energy from the forces of mortality.  Each creature within 10 feet of the corpse that exploded must make a Constitution saving throw, taking 4d6 necrotic damage on a failed save, or half as much damage on a successful one.  On a failed save, a creature can't regain hit points for 1 minute.  The corpse is disintegrated immediately after being used for the casting of this spell. 

For 1 minute after failing the save agianst this spell, a creature has disadvantage on Constitution saving throws and death saving throws, as the spell presses on a creature's life force with the weight of mortality.     

At Higher Levels.  When you cast this spell using a 2nd-level spell slot or higher, the damage increases by 1d6 for each spell slot level above 1st.