Black Cauldron [AoD]

You cast a heretical ritual that defiles and desecrates the surrounding landscape. When the casting of the spell is complete, the noxious contents of the cauldron begin to boil and churn indefinitely, spreading a thin, necrotic mist across a 1-mile radius, 500-foot tall cylinder centered on the cauldron. Over the course of 10 days, the mist defiles all earth, water, and air within the area, causing plants to wither and and wildlife to turn rabid. Bodies of water become stagnant and diseased, food and crops turn poisonous, and both natural and magical healing are stifled.

After the 10th day, a creature who remains within or enters the desecrated area must make a Constitution saving throw. On a success, the creature is unafflicted, though it must repeat the save again after 1 hour has passed if it remains in or re-enters the area. On a failed save, the creature becomes afflicted with a rotting malady, suffering the first condition on the list below (poisoned). An afflicted creature must then repeat the saving throw every 24 hours thereafter, gaining the next condition from the list with each failed save.

Creatures that make these saving throws while within the desecrated area do so with disadvantage, and they cannot regain hit points nor be cured of the malady by any means while within the area. If a creature is immune to any condition on the list, it continues its progression on the list normally, ignoring the effect of that condition. If an afflicted creature within the area is reduced to 0 hit points, it dies and raises 24 hours later as a zombie that is loyal to the caster of the spell.

The malady is a necrotic curse that can be cured by the remove curse or greater restoration spells. The conditions imposed by it proceed in order of: poisoned, deafened, blinded, incapacitated, stunned, paralyzed, unconscious.

The cauldron has 100 hit points and an AC of 15, and is immune to fire, necrotic, poison, and psychic damage. Destroying the cauldron ends the spell, allowing victims to be healed and returning the land to normal over the course of 10 days.