Wraith Walk

You take on a spectral form, stepping through enemies you can see, invoking death's chill. When you cast this spell you immediately move up to 90 fee, and can move through creatures as if they were difficult terrain. a creature you move through must roll a Constitution saving throw. on a failed save, the target takes 3d6 necrotic and 3d6 cold damage, and half as much on a success. A creature cannot be affected by the damage of this spell more than once per casting. Your movement does not provoke attacks of opportunity for the duration of this spell. 

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