Sword rain

You summon a variety of blades in the air in an area of 10 ft in radius over a point you can see within 30ft and let them fall upon the creatures within the area. All creatures within the sphere must succeed on a dexterity saving throw. On a failed save each creature takes 6d8 piercing damage, or half as much on a successful one. The radius is then filled with non-magical swords making it difficult terrain. the swords disappear after a minute.