I played this quest last night with some success. However we had a situation that we were not 100% clear on and are hoping someone might have an answer…..
We had two of the trolls engaged with us (Tom and Bert if I remember correctly). The troll Tom had the shadow card dealt to him revealed as the Troll Key.
The troll key has the card effect: "If Troll Key is discarded, resolve its "When Revealed" effect if able. When Revealed: Attach to a Troll enemy. Response: After attached Troll enemy takes damage as the result of an attack, the first player may exhaust Bilbo Baggins to claim this objective and attach it to him."
Obviously we ignore the "When revealed" effect as it was dealt as a shadow card. The confusion came over the response part…. As "Shadow cards remain on the enemy to which they were dealt throughout the combat phase. If that enemy leaves play, discard its shadow card from play. At the end of the combat phase, discard all shadow cards that were dealt this round." (page 20 core rules).
In the combat phase Legolas attacked and damaged the troll Tom (but not killed, so he stayed in play). And as the troll key states "After attached Troll enemy takes damage as the result of an attack, the first player may exhaust Bilbo Baggins to claim this objective and attach it to him." And as the troll key is still in play because you only discard shadow effects at the end of the combat phase, can we exhaust Bilbo to claim the objective even though it was dealt as a shadow effect?