A really amazing attachment, especially at high player counts where seeing lots of locations is quite common and there are some brutal one, from X where X is the number of allies/characters controlled by the first player", to anti-Northern Tracker ones, to those which block canceling encounter effects and so forth. It saved our asses a few times and I always try to include it in a Spirit deck of a 4 players Fellowship.
Attach to a hero.
Response: After a location is added to the staging area, attach Thrór's Key to that location. While attached to a location, Thrór's Key gains: "Treat attached location's printed text box as blank, except for traits."
On the Doorstep #16. Spirit.