I tried getting some clarification on this in another thread, but it didn't go anywhere, so let's try again. This came up during my last play through of the "Battle of Five Armies" and Bolg.  I took "immune to player card effects" to mean that cards that did direct things to him (like lowering his stats or direct damage via Gandalf or Descendant of Throndor) could not be used. Likewise, one couldn't get any affect from something like a Forest Snare on him. However, I'm not so sure about card