Breath of the Underworld

You radiate an aura with a 30 foot radius centered on you. Each affected creature within the area of affect suffers 5d8 points of necrotic damage, a Constitution saving throw for half damage. Creatures within the area of affect at the start of their turn, continue to take damage until a saving throw is made with damage reducing by one die on each subsequent round.

At higher levels. When you cast this spell using a spell slot of 5th level or higher, the damage increases by 1d8 for each slot above 4th.

The spell has no effect on undead, elementals, or constructs.