Schoffner's Catalogue isn't a good card on its own. The reason is obvious; having to pay 2 resources, a card and a play action for 5 resources is a lousy deal. Yes, you can pay for other investigators' stuff, but the item assets-only clause is a severe limitation in a game with events, spells, allies and whatsnot. Also note that most investigators tend to play their items early-to-mid game, making Schoffner's Catalogue less relevant as the rounds pass by.

Still, it's a good card for a few investigators:

• Bob Jenkins really likes this card, as he can play it as an extra action and use it to pay for all his other items. The catalogue as an item based support package is literally designed for him.
• It's also decent for parallell Daisy Walker, as the catalog is pocket sized and requires no hand slots. And =Daisy can use it to pay for her other tomes and as a target for tome-related shenanigans.

Other highlights:

• Recursion. The catalogue is automatically discarded when empty, making for an easy combo with Scavenging. With Scavenging (2) you can even get it in play without spending a play action.
• Tome interactions. Whitton Greene to find it, Library Docent to bump it or play it for free, etc.
• It's also a possible source for harvesting secrets (Eldritch Sophist).

All in all, a niche card that works well for Bob and possibly parallell Daisy. Other investigators will have to find ways to make the catalogue more efficient to make it worth their time - such as a support Minh with Scavenging or a Yorick build with enough costly items to make the catalogue worth using his ability on.

Q: When no more set-aside Monster enemies left, can I trigger action ability on this card to discard?

RR "Target" says :

The term "choose" indicates that one or more targets must be chosen in order for an ability to resolve. The player resolving the ability must choose a game element (usually a card) that meets the targeting requirements of the ability.

If an ability requires the choosing of a target, and there is no valid target (or not enough valid targets), the ability cannot be initiated.

This card has an unexpected synergy for an investigator who came out years earlier. Jim Culver, musician, can use this spell to great effect. His power lets him to treat the elder sign as a skull, and skulls as +0. But that’s different than the token.

So when Jim puts Flame into play, he’s only afraid if he draws an actual zero (on hard or expert, there aren’t any +1s in the bag.)

This makes it much better for him than shriveling, which can trigger off during a skull token even if it counts as a zero.

LivefromBenefitSt's review of the first Law of this set pretty much sums up why this might be the most annoying Treacheries in the game.

Fun fact for this particular card is that, if I'm not mistaken, this is the first instance of an effect that fundamentally changes the game depending on the language you are playing (card titles differ in word length in different languages). So for example Look what I found! is playable while you hold Pandemonium and can be discarded to get rid of it if you are playing the game in English; while it's the opposite (dead card in hand) if you are playing in Spanish ("¡Mira lo que he encontrado!").

(If you've seen The Music Man, proceed. If not, have a look here first: youtu.be )

+++

CASH for the Lucky Dice, CASH for the Rabbit’s Foot.

CASH for the Leather Coats, CASH for the Trench Coats.

CASH for the Fancy Goods, CASH for the Track Shoes.

CASH for the Tokens and the Totems and the Moonstones.

CASH for the Thermos, Pipes and Painkillers.

CASH for the Shovels and the Lanterns and the Newspapers.

Look, howdoyafight, howdoyafight, howdoyafight, howdoyafight, howdoyafight? HOWDOYACLUEVER? Howdoyafight?

Ya can Move, ya can Draw, ya can Parlay, ya can Fight,

Ya can Cluever, Cluever, Cluever, ya can Fight, ya can Fight,

Ya can Move, Draw, Play, Fight, Cluever, Cluever, Cluever,

Ya can Fight all ya wanna but it’s different than it was!

No it ain't, no it ain't, but you gotta know yer inventory!

~Shh shh shh shh shh shh shh~

Why it's the Axe / Horse combo made the trouble,

Made Survivors wanna blow, wanna get, wanna get, wanna get up and blow

Seven, eight, nine, ten, twelve, fourteen, twenty-two, twenty-three cash on any fight they meet!

Yes sir, yes sir!

Who's gonna draw and play a little batty two-hand break-onna-skull anymore?

Howdoyafight, howdoyafight? HOWDOYACLUEVER?

Gone, gone, gone with the Thermos, Pipes and Painkillers.

Gone with the Derringers, the .41, the .18.

Gone with the Signs and the Knives and the Vests.

Ever meet a fellow by the name of Bob?

...Bob?

............Bob?

..Bob?

........Bob?

.....Bob?

..................Bob?

..........................Bob?

Bob!

NO.

Just a minute, just a minute, just a minute!

Never heard of any salesman Bob.

Well he knows what’s in your inventory!

Knows what’s in my inventory?!

What's his stat line?

Never worries 'bout his line!

Never worries 'bout his line?!

Or a doggone thing!

He's just an all-in, neck-wringing, dumb luck, hard knocks, double-nothing, high-rollin’,

Turns-into-a-great rogue salesman!

That's Mister Bob Jenkins, Bob Jenkins!

What's the fellow's line? What's his line?

He's a fake, and he shouldn't know your inventory!

Look, howdoyafight, howdoyafight, howdoyafight, howdoyafight?

He's a Shrewd-Deals man!

He's a what? He's a what?

He's a Shrewd-Deals man and he sells Catalogues

To the ‘gators in the town with the big Thompsons

And the rat-a-tat guns. Cigarette case, cigarette case!

And the Lupara, the Lupara, and pocket-Colt, too!

With a shiny gold pock-et-watch for yer big red glove-wearin'-

Weeell, I don't know what’s in yer hand but I do know

You can't make a living playin’ other people’s cards, no sir.

“You owe me one”, perhaps, and here and there a Teamwork-

No, the fellow plays hands. YOUR hands! I don't know how he does it!

But he lives like a king! And he dallies and he cluevers and he picks and he shines.

And with a transaction, certainly, boys, what else? The gator pays him!

Yes sir! Yes sir! Yes sir! Yes sir!

With a transaction, certainly boys, what else?

The gator pays him!

Yessssir. Yessssir.

BUT HE’LL KNOW WHAT’S IN MY INVENTORY!