Arms of the Darkweaver

You invoke the energies of the Shadowfell and call forth the power of a Darkweaver. Tendrils of shadowy smoke erupt from you and batter all creatures within 10 feet of you. Each creature in that area must make a Strength saving throw. On a failed save, a target takes 2d6 necrotic damage and is knocked prone. 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.