Black Ice

You freeze the ground in a 10 ft radius circle at a point of your choosing within range. Any creature who starts its turn or moves into the area for the first time makes a DEX saving throw or falls prone, taking 2d8 cold damage. The ground becomes difficult terrain and creatures must repeat the DEX saving throw when they attempt to stand up, taking 2d8 cold damage each time they fail. On a saving throw, they take half as much damage and do not fall prone.  They still must repeat the saving throw each turn.   A creature resistant or immune to cold damage automatically succeeds on the saving throw.

At Higher Levels: When you cast this spell using a spell slot of 3rd level or higher, the damage increases by 1d8 for each slot level above 2nd.