Ennui's Searing Pillory

A pillar of roiling black flame emerges from the ground in a 5 foot cube within range. Any creature of my choice within 10 feet of the cube must make a dexterity save. On a failed save a chain comprised of the same black flame lashes out and wraps around them inflicting 2d8 fire damage and the restrained condition. On a restrained creatures turn they may use their action to make make a Strength or dexterity save (Their choice) to escape the chains grasp or another creature may use their action to make a strength save to break them free. Any creature still restrained in this way at the end of their turn takes an additional 1d8 fire damage. On the Casters turn they may use an action to cause additional chains to re-lash towards targets within range.