Note that, due to the difficulty to properly combine Messenger of the King with the intent of this new contract, we at ALeP we have proposed a new wording for Messenger of the King inside our Free to Choose List, that you can find at this page alongextendedparty.com

The new wording of Messenger of the King basically turns the MotK hero into a starting hero in all respects, so if you want to use MotK with say At the End of All Things, the MotK will be one of your two starting heroes with all that entails (like not being able to gain resources from attachments). The same would be true for something like The Grey Wanderer or Bond of Friendship, with the MotK hero taking the place of a starting hero.