You create a wave of ice shards that rise out of the ground along a line 5 feet wide and 30 feet long. When you cast this spell, you can choose to teleport to an unoccupied space that is completely within this area, halting the advance of the wave up to that point and thus shortening the line. Each creature in the spell's area must make a Dexterity saving throw, taking 2d10 piercing damage and 3d6 cold damage on a failed save or half as much on a success. The shards leave a wake of ice in their path, causing the ground in the area to become difficult terrain until the end of your next turn.