So for 4XP I can now have everlasting ammo thus totally breaking the balancing of firearms vs melee.

Good job FFG ;)

But seriously in those gimmicky sniper builds this is an auto include, the single biggest issue I had playing my Mark Harrigan sniper deck was running out of ammo. For 4 XP I can now never run out of ammo OR have to worry about shooting enemies off teammates.

Many of the excellent reviews compare J.K. to Dr. Milan Christopher, but it's also helpful to consider J.K. in comparison to a different card - the humble Laboratory Assistant.

Similarities:

• draw cards when played
• Seeker
• icon for skill tests
• Ally
• Miskatonic (so most investigators can have loads of ally slots, thanks to Miskatonic Archaeology Funding)
• even cost

Laboratory Assistant advantages

• costs less
• 2 sanity
• increases hand size by 2
• 0 xp (versus 2 with the new taboo for J.K.)
• Science

Jeremiah Kirby advantages

• 2 health
• +1
• draws more cards, probably
  • never, ever draws weaknesses
• Wayfarer

They're curiously similar cards in that they front load most of their benefit to the time they're played. That makes them particularly attractive with cards that trampoline them:

• Calling in Favors - bonus points if you can manage to use the point of soak before you bounce them. This makes a big investment in a high-xp ally more likely to work out.
• A Chance Encounter(0)
• Crypt Chill?
• I'm probably missing some...

Has anyone tried all these in a deck together? I'm considering it.

The team play feature is not just good for sharing the love of assets, but also allow others taking the play quota to skip Attack of Opportunity when playing those assets. Making this a great card for soak, Firearm, Spell users looking to refresh Asset even while in the mess of fighting. (The one who take play action to play Ever Vigilant (4) does have to deal with one AoO.)

If you are coming to rescue someone from enemies, you might not even have to engage it or risk friendly-fire. Instead just play this card. They might have just the asset that help dealing/evading that enemy on hand, only if they are Fast... well Ever Vigilant (4) is going to grant them that dream. It's like an uber-one-off-Fence comes flying to them : Works with all traits, no setup, and get both Fast and -1 discount! This allow team to recover from unlucky setup turns and make a come back even if enemies are already sticking in their threat area.

Since this card is looking to be the strongest at the start of scenario where you are all together, you may wish to communicate if you managed to mulligan into this card or not to influence mulligan decision of the other players in your party. (Or use Stick to the Plan)

Mulligan occurs in player order, the with this card as the lead may allow more efficient setup. Especially that it is "4 assets in total" as a group, you need to talk about how you share this quota. Below are relevant rules for reference.

Appendix III: Setting Up The Game

• ...
• Choose one of those investigators to be the lead investigator for this game.
• ...
• Draw opening hands. Each player draws 5 cards. Each player, in player order, may mulligan once at this time.
• ...

In Player Order

If the players are instructed to perform a sequence "in player order," the lead investigator performs his or her part of the sequence first, followed by the other players in clockwise order. The phrase "the next player" is used in this context to refer to the next player (clockwise) to act in player order.

The "new" double-attribute based skill cards can make Lt. Wilson Stewart absolutely amazing.

Unlike other skills cards (like Strength in Numbers) which only gain icons while committed, these skill cards all have the added text: "While [Card] is in your hand ... it gains {skill 1} icons equal to {skill 2} and {skill 2} icons equal to {skill 1}"

"From FAQ - A: The abilities on skill cards are only active while they are being committed to a skill test, unless otherwise specified."

• Defensive Stance: Heal horror/damage from Lt. Wilson Stewart AND gain resources
• Survey the Area: Draw cards AND gain resources
• Occult Theory: Draw cards AND get + on your next test.
• Dauntless Spirit: Heal horror/damage from Lt. Wilson Stewart AND get + on your next test.

With just 4 and 4 , discarding Survey the Area to Lt. Wilson Stewart would draw 4 cards and gain you 4 resources at fast speed.

Ina 3 or 4 player game, this reads a bit like fast, look at 9 or 12 cards from the deck and pick one player to draw the 3/4 of them worst cards (because the cards aren't from your own deck they probably won't be optimal).

It actually compares pretty well even against Black Market (which itself is a very strong card). Compared to black market in a 3-4 investigator multiplayer game...

Pros
-Drawing cards is usually better than setting aside to use only for this turn
-Is free, black market costs 1 resource
-You get to look at 9 or 12 cards and pick from those, not just 5

Cons
-Drawing this in upkeep phase, you have to decide which pile before the mythos phase (black market happens at investigator phase when you have more info to decide better)
-Removing cards from your deck can rarely cripple your deck if it relies on key cards or combos
-You only get 3 or 4 cards instead of 5
-You cant use other investigator's card for combos

I think I'd play this in a 3 or 4 player game.
In a 1 or 2 player game, black market easily.
Or do both if you can/want, they're both good. More cards means more options, more icons for commit, more passed tests means more wins.

I think a lot of people know this but removing cards from the top of your deck is not usually considered a big detriment because you generally do not know what cards are coming up. As far as you the player is considered, a card removed from the top is the same as a card removed from the bottom, and possibly a card you would have never seen anyways (ignoring decks that cycle quickly).