You create a wall of oily, black smoke on a solid surface within range. You can make the wall up to 30 feet long, 10 feet high, and 1 inch thick. The wall is opaque and lasts for the duration.    When the wall appears, each creature within its area must make a Dexterity saving throw. On a failed save, a creature is covered in a sticky, heavy film of shadow until the spell ends. A creature covered in the shadowy film is blinded, takes a −1 penalty to its AC, and can’t benefit from being invisible. Furthermore, the first time a creature enters the wall or ends its turn there, the creature must make the Dexterity saving throw.    A creature covered in the shadowy film can take an action to wipe off the film, ending the effect on itself.