this was a topic awhile back (wondering how treasure cards work, how they go into deck, etc). courtesy of Hastur360 on CGDB:

"Treasure:

A player is permitted to add a treasure card to his deck if both of the following conditions are met:

1. The players has discovered the specific treasure card he wishes to use through game text in a previous scenario using the same group of heroes he is currently playing with.

2. The specific treasure card belongs to a treasure set that is listed in the setup instructions for the scenario currently being played. The treasure set icon appears in place of a sphere icon on the treasure cards, and can also be used to identify which scenario it can be discovered in.

Any treasure card that meets the above conditions can be added to a player's deck during the setup of a scenario. No more than 1 copy of any treasure card, by title, can be added to a player's deck. Treasure cards added to the deck do not count towards that deck's 50 card minimum."

Which means that none of the treasures in The Hobbit(s) can be used in any of the previous Quests.

Bullroarer Took said:

right. they established that in in the first article that revealed this expansion, i think (either that, or the second one).

Dain Ironfoot said:

And as usual I stone cold missed it!

Bullroarer Took said:

haha. no worries! it happens!

and it's both a blessing and a curse. blessing cuz it adds uniqueness to the saga expansion; a curse cuz i'll want those cards in every deck! haha.

Was there anybody NOT thinking about Mithril coat on Bilbo?

There is still a chance for that Treasure card in the next Saga Expansion of the Hobbit. As story wise he does not get that until he and the dwarves have already driven off Smaug.

Right, I didn't expect it until e Lonely Mountain, but I was hoping to be able to use it on other adventures.