Cryo Bomb

You send a frozen drop of water to an area within range and cause an explosion of cold air, sending ice shards flying, damaging any creature in a 30ft radius and causing the area to be rough terrain. Any target creature in the area of effect must make a Dexterity saving throw, suffering 10d8 Cold Damage and 4d6 piercing damage on a failed save or half as much on a successful save. 

Creatures who fail their save in the target area become encased in ice and must succeed on a strength saving throw or be incapacitated. A creature incapacitated can continue to make this saving throw at the start of each of its turns. 
The rough terrain reduces your speed by half and counts as slippery ice, causing creatures who move across the ice for the first time on a turn make a DC 10 Dexterity (Acrobatics) check or fall prone. In addition, the ice remains in target location for 1d4 days before it melts away. 

At Higher Levels. When you cast this spell at a higher level, it's damage increases by 1d8 cold damage  and 1d6 piercing damage for each level.