Magnify Gravity

Duration: 1 round
The gravity in a 10 ft radius sphere increases for
a moment. Each creature in the sphere makes a
Con save. On a failure, a creature takes 2d8 force
damage, and it's speed is halved until the end of
it's next turn. On a success, a creature takes half
as much damage and it's speed is unaffected.
At Higher Levels. Each extra spell slot increases
the damage by 1d8.