We were playing the third quest from the Core set and ran into a situation not adequately covered by the rules:
The Nazgul attacked, and it has the ability that when a shadow card effect on it resolves, the defending player must choose and discard one character from play. So the combat went as follows:
1. Nazgul attacks.
2. Gandalf defends.
3. Shadow card effect resolves, I choose to discard Gandalf.
The question is what happens next? Does the attack become "No Defenders"? If so, would the shadow card's effect possibly change retroactively? This didn't seem correct to us, so we determined that since Gandalf was declared as a defender, the attack was defended, and thus all of the Nazgul's damage went to Gandalf, even though he was in the discard pile. I'm not entirely satisfied with our resolution of that combat, though.