Vicious Vapors (5.5e Patch)

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 your later turns, 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 has the Poisoned condition until the start of your next turn. On a successful save, it takes half as much damage only.

Using a Higher-Level Spell Slot. The damage increases by 1d12 for each spell slot level above 2.