You create a 20-foot-radius Sphere of yellow, nauseating gas centered on a point within range. The cloud is Heavily Obscured. The cloud lingers in the air for the duration or until a strong wind (such as the one created by Gust of Wind) disperses it.
Each creature that starts its turn in the Sphere must succeed on a Constitution saving throw or have the Poisoned condition until the end of the current turn. While Poisoned in this way, the creature can't take an action or a Bonus Action.