So I was fiddling around with the Deck of Many Things again (again again) and yesterday's first card was the Throne (and it took a whole six cards to get to the Void, ah well).
So I was thinking once again about what scale of Keep you should get from that card.
There's a suggested one in the Book of Many Things, which I have a nice hardback of that goes with the DnD versions of cards including but not limited to the traditional Deck. It doesn't give prices for individual stronghold parts and is an adventure location by design, so it's more about clearing out the Stronghold than just like tada have a castle.
The internet reckons the old Stronghold Builders Guide has a listed price of 70,000gp for their Cheap Keep, but the SBG prices for ANYthing building wise are in no way compatible with Pathfinder 1e prices from Ultimate Campaign.
... just looked up Building prices and found
https://www.d20pfsrd.com/gamemastering/other-rules/downtime/rooms-and-teams/ lists more building components together, including ones from other books, so you too can price a Blood Spa or a Mystic Greenhouse.
... searching my own journal for Stronghold has very much the same topic come up a lot...
I don't think the rules as written even slightly hint that you can pull a fully stocked library along with your Keep, probably just fortifications and some basic wooden furniture. But I always skip to wanting to put a library in it. Obviously. Chanter's House library with 22,000 books would be so lovely. And libraries do come up in Pathfinder Adventures but for some reason the modules don't often expect you to try and loot the place. So I get stuck reading the Acadamae of Secrets adventure and want to loot something the module treats as scenery, so then in other journal entries I try and math the weight of all the books... which may or may not make any gold piece sense at the end of the day but that is, of course, not the point.
I keep trying to figure out the Library prices and what would be comparable prices between the SBG and UC, because the SBG has library book lots that give you a different bonus.
UC has Book Repository for a one topic +3 or Magical Repository for Knowledge Arcana and Spellcraft +3, +4 if you're doing magic item or spell research.
There are prices listed for magic item design that depend on the amount of bonus.
Skill bonus (competence) Bonus squared x 100 gp
UC libraries give a *circumstance* bonus, and different bonuses are x 1000gp or x 2000gp even. So it won't be the same x. But that whole section is bonus squared.
So to figure out the cost of a +6 instead of a +3 library, even though +6 is only a possibility in SBG:
Basic Repository costs 460gp, Magical Repository 730gp
I am going to knock 10gp off each and put it back on later, purely because I can see the multipliers work tidy without the 10gp, so lets call that the shelf costs or something.
A +3 bonus costs (3*3)*something gp.
450/9=50
720/9=80
So a +6 library for one skill is (6*6)*50gp = 1800gp
or Magical is (6*6)*80gp = 2880gp
Stick the spare tens of gp back on the price and it scales in the same way as any other bonus, I think.
A comprehensive Library has 9 Knowledge skills plus a Magical bit, so 9*1810= 16,290gp
+2890 = 19,180gp
Minimum size 40 square maximum 120. You could say a library needs more squares to be more comprehensive but does it really need more than three times more? SBG has it take 1 lot for +2, 3 lots for +4, and 6 lots for +6. UC's +3 is between those, but call it 2 lots for being smaller than +4 and bigger than +1, and then you get to only needing *3 the space, so it fits in that 12.
Fortification costs 300gp per room, or 3000 total for this 10 room library. It includes fireproofing but for the library not the books. Furnishings to turn it from absolute utilitarian into proper fancy also cost 300gp per room, but I would argue you don't need to upgrade the book shelves so a little added fancy reading room might be more the thing. If you want to put the whole lot behind a very locked door then a vault costs 300gp too but you wouldn't get the walls as strong as the door that way. Not in 4 to 8 squares of vault. You could however fit your standard Magical Repository within the Vault, protecting the fiddly or dangerous things there. Might need more than one vault for our dreamed of +6 though.
All that fiddling with UC rules puts an upper bound of one sort on the possible.
But it is well into the conjectural to claim a library can give you that much plus, in Pathfinder rather than DnD.
Still, happier with these prices than the SBG ones, where a +6 library is 20,000gp per subject.
How you'd get a well stocked library using the Deck of Many Things... well there's the smartest way, where you never use the thing but maybe rent it to researchers for book swapsies. There's the smart way, where you use the Gems to buy mostly books, which would take one Gems card for the most comprehensive library and still leave you with spare change. Or there's the Not Smart way, where you use a Wish for it. Given that this is outside the bounds of established safe Wish granting, you will get ever so many Trouble that way.
Which is, of course, fun.
But you may also get a slightly cursed or twisted library.
... you might get ChatGPT.
... that is not fun. nope.
The library from the Acadamae has been in a hell adjacent dimension for a subjectively really long time, so having a slightly hell twisted set of books seems a very realistic possibility, for values of realistic that apply to rpgs. But Hell is Lawful and has an interesting take on Lying, ie technicalities upon technicalities but not an outright untruth. You could easily get stuck thinking you could work around that.
Best to stick with the Gems though.
... if you have time travel in a universe with Lost Knowledge, like when the Watchers Library got blown up, this seems like a very good reason to travel. It's a tiny smidge more than a Cheap Trick, but the books were created in good order, they're just being extracted and shipped forwards in time the fast way. No paradox, perfectly respectable save.
... says a time traveller with a +6 library...
Okays, plot bunnies achieved, I'll go do something else for a bit.