As an action, you can create a packet of fine gray powder. As an action, a creature can throw the packet at a point within 5 meters, where it bursts on impact. Each creature in a sphere twice as big as normal centered on that point must succeed on a Fortitude saving throw or be affected for 1 minute. An affected creature has disadvantage on attack rolls and ability checks.
A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.