Een's Shredding Aura

You conjure glass shards that take on shapes, colors, and styles of your choice. The shards spin in a dazzling display around you to a distance of 10 feet for the duration. A creature in the aura of shards has disadvantage on the first attack roll it makes against you each turn, and when a creature enters the spell's area for the first time on a turn or starts its turn there, it must make a Dexterity saving throw, taking 3d6 slashing damage on a failed save, or half as much damage on a successful one. 

At Highter Levels. When you cast this spell using a spell slot of 4th level or highter, the damage increases by 1d6 for each slot level above 3rd.