I'm surprised there isn't a Rosie review already.

Rosie Cotton is amazing, and an absolute auto-include in Hobbit decks because of the versatility she brings. As a 2 cost 2 ally, she is as wonderfully cost efficient as the best Spirit allies and would fit in any deck even without a Hobbit hero on that alone. Where she shines is due to her ability, and the flexibility it provides players.

Because she can add her willpower to any attribute for a Hobbit hero, she becomes the equivalent of Celebrían's Stone, or Dagger of Westernesse, or Gondorian Shield. Except you get to decide which you need in any given round, and because the ability is an action, you can make that decision after staging so you know exactly which you need. She can also boost a defender after the shadow effect is revealed if there's a nasty attack increase.
In a Hobbit deck that doesn't typically have great defensive stats, sometimes you won't engage enemies even though you want to to proc Pippin and Sam's response, because you can't defend the attack. Rosie's ability enables the defense of some of those early attacks until you can find the Hobbit Cloak. Her ability is also not dependent on threat, so she makes a good backup to the Cloak for low threat enemies, or later in the game where your threat has crept up.

Outside of a dedicated Hobbit deck, I've used her as solely as a boost for Bilbo, where he was present simply for card draw. Would also work reasonably well with Sam in a similar context.

Fast Hitch lets her contribute to questing and combat (note the ability is once per phase). Anything that increases her willpower is great, Wild Stallion, Elrond's Counsel, The Arkenstone, Sword that was Broken are some I've used with regularity.
Note Red Book of Westmarch will only increase her willpower during the quest phase, so won't apply the boost to combat.

For fun and profit, use Sword-thain and then Rosie can benefit from the myriad of willpower boosting effects that only target heroes. Fireside Song, Celebrían's Stone, Song of Hope to name a few. MOTK will work here as well, but in my playing of it I found myself really hurting for actions until the hitches showed up, so overall would rather have her as an ally.

Great trap, especially for Dunedain decks. You'll get an enemy that is engaged with you, whereby satisfying the typical Dunedain requirement of stacking up engaged enemies without having to fight it.

This is a card I was initially very high on: Celebrían's Stone and Resourceful combined into one card is something that I'm sure few players would pass up. However after having included it in some of my decks for a while now, I have come to the conclusion that more often than not it isn't worth it, sadly. I think a lot of that is because of the stages in the game in which this card is most useful. As for the first effect, boosts are pretty much welcome at any point in the game, whether it's to give your questing a boost in the beginning while you're still trying to get your board together, or to help you power through to the finish line as the staging area starts to get more clogged with obstacles. But it's the second effect that I think poses some problems. Obviously additional resources are always beneficial, but the more the game progresses the more that additional resource starts to lose its impact as your heroes tend to be swimming in more resources than you know what to do with. At that point the second effect might as well not even exist, and if you're not able to make good use of both of this card's effects, then it's basically a worse version of Celebrían's Stone. Yes the stone costs 1 more and is restricted to , but it's worth it to not have to deal with an additional encounter card.

As a result this is a card that you'd really prefer to play early on in the game, but its very nature as a guarded card puts it at odds with that. At the beginning of the game you often simply can't afford to add more encounter cards to the staging area, forcing you to hold on to it for a more opportune moment. And of course the longer you hold on to it the less value it will bring when you eventually can play it. I've even had times where I played it into an empty or nearly empty staging area confident that I could deal with whatever it brought out, and then more often than not found myself regretting that decision. Like the top review mentions scrying can certainly be very helpful with these guarded cards, but that isn't something you may always have access to.

Long story short, this card has the potential to be powerful, but the scarce opportunities in which it can be played severely hamper its utility.

Why has this not gotten any reviews? Honestly, one of the best threat reduction in the game, and one of the very few options for Lore in this field. Simple to use, great effect, especially in solo play, and, first and foremost, cheap. I put two to three copies of this in each Lore deck I build, simply because it is so good.

Like A Test of Will, I'm not a huge fan of this card because I think it's unimaginative. Anything that just nullifies the encounter deck doesn't make for interesting player choices. Don't like a shadow effect - just pay 1 resource to cancel it!

I think it would be better if you then had to move the cancelled shadow card to the top of the encounter deck. That way it would force you to question whether you should cancel the effect: is the shadow effect worse than the encounter card itself? Is it better to let the shadow effect resolve and discard it or to cancel it and then reveal the card next turn?

Alternatively, it could force you to draw another shadow card. That way, the player had to decide whether to accept the shadow effect or potentially draw a worse one.

I know a lot of people will say that hasty stroke is not OP because it is a single use event and so you won't always have it when you need it but with all the recursive cards i.e. Dwarven Tomb, Will of the West, Map of Earnil (to fetch dwarven tomb), and now with event fetching via Spare Pipe it's generally not too far away when you need it.