This card can target any card in a players deck, including weaknesses. This aspects usefulness depends on the weakness in question:

• Some weakness do nothing, when drawn early: Abandoned and Alone, Shell Shock, Crisis of Identity
• Some are trivial when the party is spread out: Searching for Izzie, Smite the Wicked
• Some weaknesses need time before they can be solved, so it's important to draw them before the mid game: Hospital Debts, Cover Up, Baron Samedi, Angered Spirits
• Others require some preperation: Any enemy weakness, Overzealous, The King in Yellow, Final Rhapsody
• Some should be killed over and over for story reasons: spoiler

Other combos:

• Get powerful signature cards into play early: Green Man Medallion, Spirit-Speaker, Split the Angle
• Save deck space by including only 1 copy of unique or limited assets, like Lone Wolf, Dark Horse or Leo De Luca
• Can be copied wtih Eidetic Memory
• Gets better with more players, as the target card pool gets bigger and with that, solutions to challenges
• Can be played in any player window, including skill tests during mythos phase. This may save a player, as he could search his deck for the appropriate skill icons, like Guts against Rotting Remains

At the time of writing this had only been out a few days - and I've used it in 3 games...

This card is quietly awesome - if you, or a fellow investigator, have another card that you really need.

It's not flashy. It isn't fancy. There's no cool combos I can see. Letting someone draw any card from a deck doesn't seem that spectacular. But...

• your Guardian needs his Shotgun - fixed.
• Minh needs her Analytical Mind - no problem.
• Your mystic needs a Shrivelling right now, okay ... done.

No fuss, no worries about weaknesses or where it is in the deck, just for 2 resources take any card. It doesn't even cost you an action.

Okay, that is spectacular.

The down side is that 5 XP is a lot of XP. It's up against flashier cards, like the The Red-Gloved Man, Deciphered Reality, Strange Solution. And it's only as good as the card you need to grab, so it probably isn't a good pick for early in a campaign. However, later on, when you've a few high-value cards in the deck - this one is a solid choice.

(That said, for Minh Thi Phan, Analytical Mind is so central to her that I could imagine taking this early for her)

A really solid multiplayer pick.

Solo, it loses too much benefit to be worth it's XP, and Seekers have plenty of access to filtered draw through Old Book of Lore, Eureka!, and No Stone Unturned anyway.

I think this is the best card Arkham Horror: LCG has released since Higher Education. Key of Ys is absurdly broken.

For best results, try it with Duke and Peter Sylvestre as Pete. Those two allies will keep the Key in play more or less indefinitely, and you can enjoy what is effectively an 8/7/7/7 stat line. That is totally gamebreaking.

Or try it as Yorick. He can also use the Peter Sylvestre combo, and if the Key somehow does get discarded, Yorick can just play it back! (More often than not 10 discarded cards actually helps him, too.)

Survivors are best poised to take advantage of the Key, but really, anyone can put this to great use.

Yes, it's 5 XP, and you need other sanity-soaking assets in play for it to really work, but the benefits it grants are so absurdly strong that these drawbacks don't come close to balancing it. No matter who you are, the Key makes you an all-around dominant investigator. This card makes Wendy fight like Zoey and Skids resist treacheries like Agnes. What is more, it augments every investigator's strengths, to the point that even the Expert chaos bag stops being that scary. No other card in the game comes close to that.

The "discard the top 10 cards of your deck" proviso is totally irrelevant unless the scenario features Beyond the Veil. Even then, you might not draw Beyond the Veil, and if you do, you can just be careful about keeping the Key in play. That's not a major concern at all.

Not the most efficient use of XP. Compare this to Time Warp; both allow you to draw an extra chaos token, but "Eat lead!" only works for Firearm attacks, and forces you to spend ammo on top of that, and has to be played in advance (before you know whether you'll need the extra token or not).

Now, you can get even more tokens from "Eat lead!" if you so desire—but how many tokens do you really need? There’s major diminishing returns here, as each chaos token pulled after the first contributes less and less to your odds of success. Furthermore, ammo is precious. Even spending 1 extra hurts quite a bit, let alone 2 or 3. This really limits the effectiveness of this card with Shotgun or Lightning Gun, since the ammo is just so precious. It's a bit better with the .32 Colt, but I don't think I'd rush out and spend my XP on that.

I’m not saying this card has no place at all. "Worse than Time Warp" is not the same thing as unplayable. A janky Double or Nothing/Shotgun/Extra Ammunition deck is probably pretty excited to see this card. And with Stick to the Plan, for which both Extra Ammunition and "Eat lead!" are valid targets, these elaborate multi-card combos are more achievable than they first appear. But generally speaking, this card isn’t that powerful for 2 XP. That’s disappointing, since Firearms could have used a stronger buff than this.

A card poised to take Arkham Horror by storm (get it?).

I don't have to say much. Most investigators will benefit from this, especially if they have any way of off-shoring sanity to other assets (it has been confirmed the "you" is your investigator card).

So if you are a Mystic, Survivor, or Seeker you have assets that can help shield your Key.

Guardians without access to these card pools will struggle, but even they have beat-cops to take a few hits to keep the key around longer.

Rogues also struggle a bit to use this card without those dips due to ally selection, but they have a few things that can work.

Solo, this card is a monster. Multiplayer, you probably will have 1 person who is considering it and is trying to build around it.

Let them. Because once it gets 2 or 3 horror on it, they become hyper efficient.