Ahmet'kar's Gravitational Anomaly

You create a 20-foot radius sphere at a target point you can see within range.

When a creature enters the spell's area for the first time on a turn or starts its turn there, that creature must make a Constitution saving throw. They take 4d8 force damage on a successful save, or half as much on a failed one. Creatures that fail the saving throw are knocked prone.

The area is treated as difficult terrain for all types of movement., and any creature capable of flight or hovering cannot do so inside the sphere.

Starting from the turn following the casting of the spell, you can move the sphere for up to 20 feet per turn as a bonus action.