Sylsatras Gravity Dampener

You loosen the ties of gravity in the affected area for 1 hour. All creatures within the spells area have advantage on Dexterity saves, ranged attacks made from within, or through, the spells area do not have disadvantage for crossing their first range increment, and all creatures gain a Flying speed of 20 feet. At the end of their turn, creatures without an innate flying speed descend 10 feet towards the ground.