Thioasatonic Burst

You hurl a vial of open skunk spray to a point within range and call forth the powers of rot.  All creatures within 1/2 mile must make a constitution saving throw vs your spell save dc +5 (including yourself). On a failed save the creature suffers 10d8 necrotic damage (Half on a successful save), and has disadvantage on all rolls until they succeed on the save.  At the end of each round each creature must repeat the saving throw or suffer an additional 5d8 damage. If a creature fails multiple saves in a row they suffer 1 level of exhaustion to a maximum of 5 levels of exhaustion.  Furthermore, this spell can not reduce the hp of a creature with a positive constitution modifier to below 1.  

Creatures who can not smell are unaffected by this spell

Any creature that naturally has a sense of smell but has had its sense of smell removed by magical means have advantage on the saving throw at all times regardless of an failures. 

Using the Cleric Class Feature Divine Intervention will grant the Cleric Immunity to all of this Spells Effects. 

The Caster may dispell the effect willingly after a minimum of 5 rounds have passed otherwise The effects of this spell can only be dispelled by the effects of Miracle or Wish.  Doing so is considered, for the purposes of both Miracle and Wish, as replicating the effect of an 8th level spell.