Hunger of the Deep Forest

Level 3 Conjuration (Druid, Ranger)
  Casting Time: 1 Action
Range: 150 feet (20-foot sphere)
Components: V, S, M (a piece of thorny vine)
Duration: Concentration, up to 1 minute

  You conjure a deadly area of thorny vines and toxic. A 20-foot-radius Cube of thorny vines and poisonous gas centered on a point you can see within range and lasting for the duration. The area is Difficult Terrain and filled with greenish mist that hangs heavily over the writhing vines making the area Heavily Obscured, giving creatures fully within it have the Blinded condition. The poisonous lasts for the duration or until a strong wind (such as one created by Gust of Wind) disperses it.
  Any creature that starts its turn in the area takes makes a Constitution saving throw, taking 2d6 Poison damage and has the Poisoned condition until the start of it next turn or half as much damage and not be Poisoned on a successful one. When a creature moves into or within the area, it takes 2d4 Piercing damage for every 5 feet it travels.
  Using a Higher-Level Spell Slot. The Poison damage increases by 1d6 for each spell slot level above 3.