Wall of Velocity

You conjure up a wall that accelerates or decelerates objects that pass through it at a point you can see within range. The wall appears in any orientation you choose, as a horizontal or vertical barrier or at an angle. It can be free floating or resting on a solid surface.  You can make the wall up to 60 feet long, 20 feet high, and 1 foot thick, or a ringed wall up to 20 feet in diameter, 20 feet high, and 1 foot thick. You imbue the wall with a force that either decelerates or accelerates creatures or objects that passes through the wall. Choose acceleration or deceleration as the walls effect. When the wall appears creatures are subject to the effects of the wall.

Acceleration.  The wall of potential energy propels things that enter the wall at higher speeds.  Any creature that enters the wall has their speed doubled, advantage on Dexterity saving throws. Any ranged weapon attacks that pass through the wall's space deal extra 2d8 force damage on hit. 

Deceleration. The wall of fills with negative force. Any creature that enters the wall have their speed halved and disadvantage on Dexterity saving throws. Ranged weapon attacks that enter the wall's space automatically miss as the weapons velocity is brought to zero by the wall.