You conjure a swirling poisonous miasma around yourself. For the duration of the spell, you are lightly obscured. When you cast the spell, and as a bonus action on each subsequent turn, you can cause the vapors to surge out and swirl around up to three creatures of your choice within range. Each creature must make a Constitution saving throw. On a failed save, it takes 1d12 poison damage and becomes poisoned until the start of your next turn. On a successful save, it takes half as much poison damage and is not poisoned.