Ancient Death Rancor

You manifest the Black Flame in its purest form.

A torrent of black flame and souls of the damned explodes out of you in a 30-foot-wide burst. Each creature within the radius must make a Constitution saving throw. On a failed save, a creature takes 6d8 fire damage and 6d8 necrotic damage and cannot have its Hit Points restored until the end of its next turn. On a successful save, it takes half as much damage but still suffers the additional effects. Constructs automatically succeed and take no additional effects.

At Higher Levels. When you cast this spell using a spell slot of 7th level or higher, the damages increase by 1d8 for each slot level above 6th.