Vicious Vapers

You fill the air with a poisonous vapors in a cube 5 feet on each side. A creature must make a Constitution saving throw when it enters the spell's area for the first time on their turn or starts its turn there. On a failed save, they take 1d12 poison damage and become poisoned until the end of their next turn. On a successful save, they take half as much damage and do not become poisoned.

You can move the cloud of vapors up to 20 feet as a bonus action during your turn.

Source: Kibble's Generic Elemental Spells