Amplify gravity

This spell intensifies gravity in a 50-foot-radius area within range. Inside the area, damage from falling is quadrupled (2d6 per 5 feet fallen) and maximum damage from falling is 40d6. Any creature on the ground in the area when the spell is cast must make a successful Strength saving throw or be knocked prone; the same applies to a creature that enters the area or ends its turn in the area. A prone creature in the area must make a successful Strength saving throw to stand up. A creature on the ground in the area moves at half speed and has disadvantage on Dexterity checks and ranged attack rolls. 

Flying creatures within range have to pass the Strength saving throw or fall to the floor prone.