This is a very interesting side quest. While I think it is very underrated, it can be huge at times. For example, the other day I made a Harad deck with some of the cards I own and by getting this in my hand at the beginning of the game, it almost certainly means I can get a big ally out (like Firyal, Yazan, Jubayr) turn 2, which can be huge.
It's also a really good card to consider when playing a deck with three different spheres.
Who it works well with:
Thurindir because you can dig it out for the beginning of the game.
A deck that has high cost allies.
A deck which you use three different heroes of three different spheres of influence.
My opinion: 7/10