Swamp Surge

You bring forth the essence of the Plane of Ooze creating a field of mud that surrounds you 20ft in all directions, this field moves along with you for the duration of the spell. All creatures other than yourself receive a penalty of halved movement speed and disadvantage on Dexterity Saving throws. 

The spells duration increases to 4 rounds at 5th level, 5 rounds at 11th level, and 6 rounds at 20th level.

At 15th level the field now surrounds you 25ft in all directions.