There is a rare spawn wolf, worg and instead of dealing physical damage, it does shadow damage. Located in Duskwood
but the wolf special ability is useless for him, because he deals magical damage not physical.
-Damage can be resisted
-Damage goes thru 100% armor, if not resisted
-Movement speed is normal.
-Frostwolf skin
Note: Blizzard already announced that they will be fixing this soon.