Corso's Cannonball

You touch a cannonball imbuing it with necrotic energy. When the cannonball is fired, it travels to a point of your choice within range and magically comes to an abrupt stop, hovering in mid-air before suddenly dissipating into a 30-foot cloud of noxious purple gas. All creatures within the cloud are considered blind and must make a Constitution saving throw. On a failed save, the creature takes 5d6 necrotic damage and half as much on a success. Creatures that don't need to breathe air automatically succeed on this saving throw.

A moderate wind (at least 10 miles per hour) disperses the cloud after 4 rounds. A strong wind (at least 20 miles per hour) disperses it after 1 round.