Vassilis’s Pyre Vortex

You conjure a cyclone of arcane hellfire in a 10-foot-diameter, 40-foot-high cylinder centered on a point within range. Each creature in the area when the spell is cast must make a Dexterity saving throw, taking 6d6 fire damage on a failed save, or half as much on a successful save.

As an action on each of your subsequent turns, you can move the cyclone up to 30 feet to a point you can see within range. Each creature the cyclone passes through when it is moved, that ends its turn in the cyclone’s area, or that enters the area for the first time on a turn must make a Dexterity saving throw, taking 6d6 fire damage on a failed save, or half as much on a successful save.

The cyclone leaves a trail of fire in each 5-foot cube it passes through, which lasts until the start of your next turn. The trail and the cyclone’s area are difficult terrain. Any creature that starts its turn in the trail area or enters it for the first time on a turn, takes 2d6 fire damage (no save). When the trail’s fire expires, the ground ceases to be difficult terrain.

As a bonus action on your turn, you can intensify the cyclone, increasing its damage to 7d6 for that turn only.

At Higher Levels: When you cast this spell using a spell slot of 6th level or higher, the initial, movement, and intensified damage each increase by 1d6 for each slot level above 5th (e.g., 7d6 and 8d6 at 6th level, 10d6 and 11d6 at 9th level).