Create Ice

The ground in a 20-foot radius centered on a point within range you can see chills and freezes. The ground in the area is covered with slick ice and exposed flames in the area are doused. 
When a creature moves into or within the area, it takes must makes a Dexterity saving throw or fall prone.  For every 5 feet it travels the DC increases by 1. A creature moving through the area can spend 4 feet of movement for every 1 foot it moves to avoid the Dexterity saving throw. 

If the spell strikes a body of water or a liquid that is principally water (not including water-based creatures), it freezes the liquid to a depth of 1 feet, provided that there are no creatures in it.