Alastair's Glass Shards

Shards of glass erupt from the ground in a 30 feet long  and 5 feet wide line that emanates from you in a direction you choose. Each creature in the line must make a Dexterity saving throw. A creature takes 2d12 piercing damage on a failed save and if the creature is large or smaller they are knocked prone, or half as much damage on a successful one.

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, the damage increases by 1d12 for each slot level above 2nd.