This card can be pretty useful in decks that have Beorning allies! Let’s say a Giant Bear was destroyed during combat, then the next round you can exhaust Birna to put Giant Bear back into play for one round only for one resource! At the end of the round instead of the Giant Bear being in your discard pile, he’s in your deck to draw him up again. I say a Giant Bear in play for one round for one resource is a pretty good deal for me! But there are tons of other great targets for Birna’s ability than just the Giant Bear. For example, there’s Beorning Skin-changer and Beorn himself! There’s lots of cool options with this card.

What about this card? I put it in ever deck with a ln hobbit hero!! This attachment can reduce a lot of expensive event like the gratis hunt! I play correct or i did a mistake? And with erebor hammersmith i can retake it and replay more times

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While this card is great with any Hobbit hero around note that it does not work well with the "must spend resources from 3 different heroes" events. If you discount those events you will not satisfy the requisite of spending resources from 3 different heroes so you will not be able to use stuff like The Great Hunt. But it works well with say Galadhrim's Greeting or Hour of Wrath. —

This card is great for decks that have access to the Leadership sphere and can’t defend much, so that you can return the chump blockers to your hand after they are destroyed while defending. In the next planning phase you can pay for that same ally that defended so that ally can defend against the next big attack! But where this card really shines is in the Journey in the Dark scenario, where you encounter the Balrog. When you face the Balrog, your threat is most likely 40 and above, so you are able to use the Valour action to return those allies who defended back in your hand so in the next round, you can use them again. This card helps even more if your deck can’t bring in cards quickly to your hand. This card can definitely save the day in a pinch!

Not a review, but theoretical question: what happens with the guarded attachment if the active location is discarded (e.g. with Distant Stars) and not explored?

I see that it's maybe not the perfect combo anyway (since with Distant Stars you "make a location active" instead of "travelling to" and that sadly bypasses the opportunity to draw another attachment), but I'm wondering if there is any synergy.

Sadly the attachments is placed in your discard pile in that situation. —
@alonewolf87 is that true? I thought you'd get the attachment after following the standard rules for Guarded(X): "Once free of encounters, its owner gains control of it and attaches it to an eligible card." —
Yeah, the basic rule is that once a card leaves play all attachments on it are placed in the discard pile, unless something clearly says otherwise. This contract does not make use of the Guarded (X) keyword rules, it even specify to ignore the Guarded (X) keyword if present on the loot attachment. We could argue if the loot attachment is meant to go to the staging area without a way to claim it as an objective, instead of being placed in the discard pile, but that seems very weird to me. —
What is the difference between ignore the guarded keyword and it losing the guarded keyword. As this is an ignite effect, it seems that once that part has concluded, the ignore ends (there is also no tracking to this). I'm unsure on the intention of the designers here. —
IMHO since it does not trigger when it comes into play, the "delayed effect" of getting the guarded (X) attachment should not be applied either. —
Still it must be something worth asking the developers a clarification —
You might also be able to argue that the clause about Guarded (X) clause is a constant effect, lumped in with the triggered forced to save space on the card. —
As I'm thinking about this more, there are more questions arising - for example, what if I switch the active location (e.g. with Strider's Path) and then explore it in staging area? Text on Burglar's Turn applies to ACTIVE location only, but... yeah, it would be great to ask devs about the clarification. —
I wrote to Caleb, let's see if he answers. —

At least when dealing just with just the core set, getting this card on Gimli along with 4 damage, gets him up to 8 attack. This also makes Quick Strike with Gimli very powerful as you can take out most enemies before they attack. While you can put more damage on Gimli with Citadel Plate, Dwarven Axe is a bit cheaper, which means you can get it out faster. And In most cases 8 attack is enough. That said, if you have the resources, you could always put both on and get him him to 12 attack to enable handling a hill troll or something similar in one hit.