Doomtide

You create a 20-foot-radius Sphere of inky fog within range. The fog is magical Darkness and lasts for the duration or until a strong wind (such as the one created by the Gust of Wind spell) disperses it, ending the spell.

Each creature in the Sphere when it appears makes a Wisdom saving throw. On a failed save, a creature takes 5d6 Psychic damage and subtracts 1d6 from its saving throws until the end of its next turn. On a successful save, a creature takes half as much damage only. A creature also makes this save when the Sphere moves into its space, when it enters the Sphere, or when it ends its turn inside the Sphere. A creature makes this save only once per turn.

The Sphere moves 10 feet away from you at the start of each of your turns.

Casting as a Circle Spell. Casting this as a Circle spell requires a minimum of five secondary casters. In addition to the spell's unusual components, you must provide a special component (a string of three black pearls from Pandemonium), which the spell consumes. The spell's range increases to 1 mile and its duration increases to until dispelled (no Concentration required). The spell ends early if any caster who participated in this casting contributes to any other casting of Doomtime as a Circle spell.

When the spell is cast, each secondary caster must expend a level 3+ spell slot; otherwise, the spell fails.