Bone

You do a pelvic thrust, and three femurs come shooting out of your groin at your target. If the target fails a CON save, it takes 3d4, plus your spellcasting modifier, piercing damage, or necrotic damage. If the target fails a CON save, it takes half damage. 

At higher levels, the spell increases in damage. When used as a 2nd level spell slot, 5d4. 3rd level, 7d4, and so on.