Void Storm

A sphere of Void Energy rips through a space centered on a point within range. All creatures within a 30ft radius sphere must make a Constitution saving throw against your spell save DC. On a failure creatures are pulled 10ft towards the centre and take 7d8 force damage. 

All creatures caught within the centre of the storm must make a Strength saving throw in addition to the Constitution saving throw or be knocked prone.

For each level this spell is cast beyond the 4th, this spell deals an additional 1d8 force damage