Cloud of Death

You summon a horrible cloud that kills everything it comes in contact with. If a creature starts its turn in the cloud, the target is poisoned and takes 1d6 necrotic damage. The cloud can be dispersed by any strong gust of wind.

At the end of each of the poisoned target's turns, the target must make a Constitution saving throw. If the target succeeds on three of these saves, it is no longer poisoned, and the spell ends. If the target fails two of these saves, the target is no longer poisoned, but inflicted with disease from the table below. Roll a d4. The number rolled states how many diseases of your choosing they get struck with.

Since this spell induces a natural disease in its target, any effect that removes a disease or otherwise ameliorates a disease's effects apply to it.

1. Flesh Rot. The creature's flesh decays. The creature has disadvantage on Charisma checks and vulnerability to all damage.

2. Seizure. The creature is overcome with shaking. The creature has disadvantage on Dexterity checks, Dexterity saving throws, and attack rolls that use Dexterity.

3. Slimy Doom. The creature begins to bleed uncontrollably. The creature has disadvantage on Constitution checks and Constitution saving throws. In addition, whenever the creature takes damage, it is stunned until the end of its next turn.

4. Lung Burst. The creature has trouble breathing and starts wheezing loudly, giving disadvantage to Strength checks, Strength saving throws and the Stealth skill. In addition the creatures can't hold its breath or it starts suffocating. In addition the creature's movement gets reduced by 20ft and  it can't cast spells that have a verbal component.