Shred Veins

You manifest razor-edged shards of metal in the veins of all creatures in a 20-foot-radius sphere centered on a point you can see within range.  A target must make a Constitution saving throw, taking 2d8 necrotic damage and 4d8 slashing damage on a failed save, or half as much damage on a successful one.  A creature that rolls a natural 1 on its saving throw is also blinded until it regains all hit points lost to this spell. 

The metal shards dissipate into nothingness after the damage is dealt. 

This spell has no effect on undead or constructs. 

At Higher Levels.  When you cast this spell using a spell slot of 4th level or higher, the slashing damage increases by 1d8 for each slot level above 3rd.