Mantle of Tentacles

Tendrils of dark energy erupt from you writhe around you within 10 feet for the duration. When you cast this spell, you can designate any number of creatures you can see to be unaffected by it. When the creature enters the area for the first time on a turn or starts its turn there, it must make a Strength saving throw. On a failed save, a target takes 2d6 necrotic damage and can’t take reactions until its next turn. On a successful save, the creature takes half damage, but suffers no other effect. 

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