Dimensional Blade Slash

You brandish the weapon used in the spell’s casting and make a melee attack with it against one creature within 5 feet of you. If another creature is within 5 feet of the target -5 to hit. On a hit, the target suffers the weapon attack’s normal effects and the weapon leaves a small sphere around the creature. If the creature doesn't move willingly by the end of their turn the sphere turns into a myriad of slashes going through the creature dealing 1d8 of force damage.

At level 5 the creature takes 1d8 force damage on hit, and takes 2d8 from not moving. Both damages are upped 1d8 at level 11 (2d8 and 3d8) and again at 17th level (3d8 and 4d8)