You fill the air with spinning daggers in a cube 5 feet on each side, centered on you. A creature takes 4d4 slashing damage when it enters the spell’s area for the first time on a turn or starts its turn there. Any attacks made by creatures effected by the spell must make a con save to successfully attack another target. 

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, the damage increases by 2d4 for each slot level above 2nd.