I figured most people know the optimal policy for this card by now, but getting it into a review of the card itself will help out newer people.

TL;DR:If you are using this to run only two weapons and benefit consistently from high XP weapons, you should mulligain discarding anything that is not a weapon if you didn't open with one, and then on your first turn spend all your actions drawing, and then your second turn spending two drawing and then playing this card.

Most modern guardians run 2 weapons (maybe 3 if a signature is a weapon) and two of this early, and then sometimes going down to one of this on Stick to the plan because, if you use it correctly, you will have a 90% chance of getting one of your two weapons in the first two turns using this card.

If you 'hard mulligan' (discarding literally any card that isn't your weapon if you didn't open with a weapon) you have a 55% chance to find one of the two copies of your weapon in your deck. If you don't find it in that pool, and then go for it with prepared for the worst, you have a 55% chance to find one of the copies in the top 9 cards. This means that you have an 80% chance to find the weapon, but that means 1-2 games a scenario you will fail to have your weapons in the first two turns of the game, which can get... rough, especially because if this card misses you didn't thin your deck and now will have a hellish time finding your guns.

But if you instead take your first turn entirely drawing cards, and then on your second turn draw 2 cards and play this, your odds increase, and Prepared for the worst plus the draws will find your weapon 79% of the time. Combined with the hard mulligain and you will be starting with your weapon, which means you find those guns 91% of the time. If you really slow-roll and play this turn 3 (perhaps playing an ally on your 6th action, but still getting your upkeep draw) you will nab it 95% of the time, meaning you will proably never fail to get your gun by turn 3 in any campaign, though this may lean on your flex-evader in a 4 man group.

Compare to just trying to draw into your weapon manually using the same policy. On your mulligan you got the same odds, but if you spend an entire two turns drawing you will only find a copy of your guns around 40% of the time, meaning in total you have about a 20% chance to brick out on the first two turns. So you are probably going to fail to find your weapon once, maybe twice in your campaign before turn 3.

What is worse is that the realities where you brick your mulligan can be far worse. You will fail your mulligain about 50% of the time. If you do, you still find it by the end of turn 2 50% of the time, but you have a 20% chance to take 5 turns to find your gun, meaning that a little under once a campaign you will be unarmed for half a scenario, if you can even afford to spend 4 turns doing nothing but drawing! Once you need to start doing a bad Nathaniel Cho impression your rate of finding your weapon becomes much worse and it becomes realistic you will never see a copy in a game if you need to give up by the end of turn 2.

And if you fire this off turn 1, you have a 60% chance of bricking there, and if that happens you enter the 'draw and pray' statistical reality and suddenly you start risking trauma once or twice in your campaign because your gun never shows up. So really, take it slow and don't Hail Mary Prepared For the Worst turn 1 hoping your weapons are in the top third of your deck, get it to the point where they only need to be in the top half and this card will make you a much happier camper.

This card is a huge difference maker in 2 weapon decks if used right, it is probably Guardian's most meta-defining card to the point it makes it really hard for the designers to make any sort of 'mid-grade' or 'backup' weapon in Guardian and heavily warps the card pool, but if you use it wrong it is going to make you miserable compared to running 4 weapons.

Given the arrival of crafty there is something neat about the humble lantern that allows it to shine above all other investigate tools.

Lantern is the only tool which investigates your location without having uses or exhausting, this means that along with crafty you always have a reliable, repeatable source of tool based investigate actions that also has the benefit of reducing the difficulty by 1. I tried a crafty Bob Jenkins with Scavenging and boy howdy, does having a never ending supply of free key rings, flash lights and lock picks while still be able to boost yourself by an effective 3/5 in an investigate (if you have two copies of crafty) make a pretty reliable investigator.

So lets all give it up for the humble lantern, which can be a zero cost, bonus action to play asset that even allows you to deal with the occasional annoying odd health enemy.

Does the additional cost of 4 leylines have to be paid from the investigator's resource pool (making this effectively cost 6)? Or is the reference to 'cost' because it cannot be played if there are less than 4 locations in play?

This is new boost + resource asset type. It seems that this serise is similar to PT4 serise. However, the purpose of both are quite different. 1) PT4 doesn't give any cost, but this do. 2) PT4 can boost your skill at encounter card, but this cannot. 3) PT4 can boost your skill with your resource, but this cannot. Therefore, if you're plan to boost your skill value, it may be better to use PT4.

Guardian(): Most guardians don't consider this. If you check the available list in guardian pool, there is only 1 asset to boost and most cards are event. It means that it's hard to spend resources on Prophetic for each round. However, if you're plan to use Boxing Gloves such as Nathaniel, Prophetic is good candidate. Also, Prophetic is the only asset working with Gang Up. Prophetic + Gang Up is 1 resource cost with +3 with 4 damages.

Survivor(): Like guardian, there are very few asset; available list. However, there are many good Fortune events: "Look what I found!", Lucky!, Will to Survive, True Survivor, Eucatastrophe, Trial by Fire... Thus, you can use Prophetic as an economy card. If you want to play True Survivor repeatedly without On Your Own, Prophetic is good solution.

Mystic(): Prophetic works with Spell. That's all. However, if your deck has lots of resources like P-Agnes or Dexter and you want to use Propertic as an boosting source, Arcane Studies 4 is usually better.

Off-class cards: available list I don't know which cards are good, but some economy cards work: 21 or Bust, Hot Streak.

When you see this card, your mind probably immediately jumps to Guardians. After all, they love their guns and fight boosters. And they tend to have expensive guns, win-win right?

Well... not so fast really. Guardians already have fight pretty darn well covered, and this isn't going to be a better option than most tools they can take to serve as a fight booster, especially at 3 XP. Between your base stats, Tarot Cards, Friendly Local Officers, and Evidence on a stick a guardian can easily sit at a fight value of 6 before their +4 from their Flamethrower comes into play.

Guardians also have expensive weapons, but they tend to play a singular weapon due to both how powerful their 5 xp suite are, their ability to keep it topped off with reload cards they can ensure are sticky and the strength of their tutoring. Guardians with the right mulligan policy can force their big expensive 5 XP weapon on the first two turns. So you really can't view this as a discount card for them.

Charisma to run more of your +fight allies, Reliable, Ace of Swords, heck, even Physical training (4) all kinda low key do what this card does but better? If your looking at this as a chance to really boost one attack with one card (say... you are running Shotgun for some reason and you really want to make that initial hit slam someone), you even have stuff like Enchant Weapon which for most guardians is just better and blows this utterly out of the water for weapon usage.

I am sure a guardian deck is out there that may want to spam niche weapons with huge burst swings and plays lots of armor cards too (Old Shotgun decks with pocket fulls of grenades maybe?) but overall this is just questionable in the guardian pool. Some of the tri-class 'pick a tribe' cards are economy cards, but these 3 assets are not spammable in guardian, so it really comes down to being a booster card in guardian, and guardians just do this better, and while this can stack with them, are you really going to need more than 8 deckslots dedicated to passive boosting?

I would say the most compelling case for this card is in the rogue class, though some survivors may want it as well.

Rogues can get really good at fighting, but struggle for static boosts, especially with how almost every slot they have is highly contested. They are less likely to power upgrade their weapons because while they have good higher end weapons they are less able to force them into their hand than guardians, due to lacking Prep for the worst and Mr. "Someone deserves a raise for figuring out this pun name."

A lot of rogue weapons and strategies reward you for playing more than one weapon over the course of a game, due to their low ammo counts and come into play effects, and while this won't give you discounts with Sleight of Hand it will fit nicely into sleight of hand style decks. After all, if you are running sleight of hand you eventually plan to PLAY that gun you keep flashing. And you often want to 'over-succeed' on rogues, so having a boost can really matter.

And, of course, there is the base stat gap. Even if rogues COULD run as many slotted boosters as guardian, most rogues have fairly low fight values, despite being a fighty class. They make up for it a bit with a lot of fantastic skills and events and draw to fuel those skills, but between their lower weapon bonuses and lower stats it can take a rogue a bit more effort to get to where they are hitting as often as a Guardian, let alone succeeding by whatever.

Survivors can also get some value out of this too. One unexpected candidate for this card is everyone's favorite 1 fight orphan herself, Wendy Adams, is a strangely great candidate for Bruiser, because she can combo this with her famous fireaxe to get much more serious value out of those free resources, or use it to push her attack value up to 9 for a swing.

Every single one of these cards is going to feel different just because the flavors of these tags matters so much, but I think for bruiser the question isn't going to be 'do I like weapons and maybe armor?,' because this doesn't really help those in generic cases that much. Instead, the question is 'Do I need a fight boost but lack access to one in slots I can safely give up, or am I going to be playing 3+ weapons in a game?'