Acererak's Cackle

You let out a low deep evil laugh as purple mist spews from your eyes and mouth. This mist begins in a 5 by 5 area directly in front of you, each round (Or six seconds) the mist grows by 5 ft in each direction. Everyone Inside of the mist (except those you choose not to) must succeed a Constitution saving throw or take 6d6 poison damage and poisoned. On a success they take half damage and are not poisoned. Additionally on a failed save the target cannot stop hearing a low raspy cackle for one week.