Blood Wound

You cast a dark spell over an area within 60 feet, twisting the blood of your targets to harm them from within. At a point you can see, creatures in a circle with a 30-foot radius must make a Constitution saving throw. If a target fails, they take 8d6 necrotic damage and are stunned until the end of your next turn. If a target succeeds, they take half damage and are not stunned. Creatures without blood are immune. Creatures can roll to save again at the start of their turn. 

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d6 for each slot level above 3rd.