Virtue of Annihilation V2

You summon a sphere of entropic energy, 30 feet in diameter in the air above a location within range. An area 150 feet in diameter around the sphere instantly converts the affected atmosphere into a plain that all creatures within perceive as a dreary purgatory, inflicitng a strong sense of impending doom. 

All creatures standing within the sphere's area of effect have their maximum speed reduced by 10 and take 10d8 psychic damage. At the beginning of every subsequent turn, all creatures still within the sphere's area of effect take 2d8 psychic damage and lose an additional 5 maximum speed. If a creature escapes the sphere's area of effect, they regain their lost speed in increments of 5 each turn. If a creature's speed is reduced to  0 by this spell, they become incapacitated and get drained for 1d4 wisdom each turn instead.

If you want to keep the sphere active, you can't take actions on subsequent turns for as long as you wish to keep it active. Alternatively you can dismiss the spell or,

-> As a bonus action
You may re-cast this spell and crash the sphere into the ground, dealing 5d8 magic bludgeoning damage and 5d8 necrotic damage to all creatures within the sphere's area of effect. Creatures directly underneath the sphere must make a dexterity saving throw or be incapacitated on a failed save. 

Due to the mental strain, if you use this spell as an action and bonus action on the same turn, you must make a constitution saving throw with disadvantage or be stunned for one turn on a failed save.

Upcasting
You may indefinitely increase the spell's level by permanently sacrificing 25% of your maximum hit points (rounded up) per level higher than 7, which can only be regained via a "Greater Restoration" or "Wish" spell. This spell can only be upcast via this "sacrifice method" or by circumventing the sacrifice via a "Wish" spell. 

At 8th level:
ACTION: The range distance is increased to 400 feet. The sphere grows to 40 feet in diameter. The sphere's area of effect is increased to 200 feet. Deal 10d10 psychic damage to enemies and 2d8 psychic damage every subsequent turn as long as they are within the sphere's area of effect.
BONUS ACTION: Deal 5d10 magic bludgeoning damage and 5d10 necrotic damage to all creatures in sphere's area of effect. All creatures within the sphere's area of effect must make a dexterity saving throw or be incapacitated on a failed save while creatures directly within the impact zone of the sphere automatically fail the saving throw.

At 9th level:
Creatures whose hit points are reduced to 0 by this spell get trapped within the sphere, halting any post-mortem regenerative properties and preventing all forms of resurrection short of the "Wish" spell. The creatures remain inside the sphere even after the caster dismisses the spell.
ACTION: The range distance is increased to 500 feet. The sphere grows to 50 feet in diameter. The sphere's area of effect is increased to 250 feet. Creatures within the area of effect have their speed halved, take 10d10 psychic damage, 2d10 psychic damage every following turn.
BONUS ACTION: Deal 5d10 magic bludgeoning damage and 5d10 necrotic damage to all creatures within the sphere's area of effect. All creatures within the zone must make a dexterity saving throw or lose 1 point of wisdom and be incapacitated on a failed save. Creatures directly within the impact zone of the sphere automatically fail the saving throw.