Curtain Fire

A storm of magical bullets appears to an area you can see. Each creature in a 30-foot-radius that starts their turn inside the area or enters the area must make a Dexterity saving throw. A creature takes 6d6 force damage on a failed roll, half as much on a successful one, or no damage on a natural 20. If a creature survives a minute in the storm without taking any damage, they get advantage on all Dexterity saving throws that have something to do with dodging for the next 24 hours, or until they complete a long rest.