Thousand shards of ice

You conjure a small ball of condensed Ice and hurl it at a point you can see within range. Upon arriving to the destination the ball briefly expands, contracts and finally explodes in a blast of tiny shards. Each creature in a 20-foot-radius sphere centered on that point must make a Dexterity saving throw. On a failed save, a creature takes 2d8 piercing & 2d8 cold damage.

The shards then spread out across the ground and walls in the area of effect. Shards of ice dissipate instantly in areas at boiling temperature or above, remain until the start of your next turn in areas at room temperature but below boiling temperature, remain until the end of your next turn in areas between freezing and room temperature, and remain indefinitely* in an area at or below freezing temperature. As long as they remain, the shards have the following effect:
- When a creature moves into or within the area, it takes 2d2 piercing damage for every 5 feet it travels. Creatures taking damage from shards make sounds, revealing their location if they were otherwise hidden. A creature pushed against a wall or ceiling with shards of ice in it or falling prone on top of an area covered by shards takes as much damage as if it had moved 10 feet on it. The hazard is obvious to any creature that can see it, and a creature moving of its own volition may choose to move at half speed, carefully stepping through the area and not taking this damage.

*. Lodged shards can be cleared as an action by a creature at a speed of 20 feet square per turn, cleared by an area of effect spell which would set objects on fire, cleared by increasing temperatures or covered by a layer of snow after 3 combat rounds of heavy snowing or 6 rounds of moderate snowing.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the cold damage increases by 1d8 & the lodged shard's damage per 5 feet of movement increases by 1d2, for each slot level above 3rd.