Yep.
Movement does not require LOS. Otherwise it would be impossible to willingly walk through a Fog Bank (or even a Wall of Fire or Thorns in a pinch). LOS is only required when something calls for you to be able to establish a target. So since you dont have to target your destination zone, and teleport lets you bypass the wall you can just pop right to the other side of it.
The Wraith is cool, melee Weak tokens are really handy. He can make for a pesky guard, forcing an opponent to attack an incorporeal creature with a Weakening counterattack, and as mentioned hes synergetic with Plague Master. Hes also good to sic on Grimson users, since he can pop through walls and start cutting down ranged attack damage.
He does have a few aspects to keep in mind though when compared to other creatures in the Necro toolbox:
- He is incorporeal, so he cant use Battle Fury, Whirling Strike, or Retaliate to double and triple dip his Weak chance rolls (those require Corporeal Creature as targets)
-He has the "spirit" subtype rather than "Undead", which means he can't be made into an Undying Servant or benefit from any other "undead" or Zombie/Skeleton specific synergy with Necro's other stuff
-His Upkeep +1 can add up if trying to run multiples
All in all, hes a good unit though.