Smoke Screen works a lot like Invisibility did for priests. For the cost of 2, which is INSTANT, you can play this and have your hero be elusive and untargetable. In a raid like Ulduar, where Auriaya casts sentinel blast (can't get rid of sentinel blast) This card can be useful in saving your ass. If a normal raid deck boss is about to shovel a whole heap of damage your way, you can chain the action, which will back the damage dealing up and let the boss choose a new target. At least it won't be you. I would side deck this card for sure, at the minimum.