Building/buying a library

[Matrota]

In one of my current campaigns, my DM is permitting the custom spell creation rule, and there are a few spells I'd like to create for myself. Problem is, we're on a bit of a time crunch as our party is being hunted down by 3 other groups intent on taking some powerful artifacts we've obtained. And we're also after the enemy groups' artifacts. It's a big mess.

Anyways, I'm CL 23, and have access to the spell Genesis. My idea was to make my own private demiplane over the course of a week, make it timeless, and do my spell research/crafting there. Only issue is that I need access to a library as part of the rules for crafting a spell. I imagine with a few gates and plane shifts I could move a large horde of books into my private plane, and it would also serve as a nice place to astrally project myself from for safety. However, what constitutes as a library? How expensive would this likely be? Could I just purchase books over the subjects I'm intending to craft spells for for a more condensed and cheap "library?"

[Malimar]

Stronghold Builder's Guidebook, page 25.

Short summary: a basic library (capacity: 2 lots) is 500gp, fancy library (3 lots) is 3,000gp, or luxury library (6 lots) is 15,000gp.

Filling the libraries with books costs 1,000gp per lot, if it's on a specific area of knowledge (+2 check to a specific kind of Knowledge check). You could also buy a lot of general books for 3,000 (+1 to all knowledge checks). Or you could buy a comprehensive book lot that takes up 3 lots and costs 5,000gp (+4 to a specific kind of knowledge check). Or a master book lot that costs 20,000gp and occupies 6 lots (+6 bonus to one kind of knowledge).

For your purposes, if you're cheapo, you could buy a basic library for 500gp and fill it with a lot of knowledge(arcana) books for 1,000gp and that would probably be enough.

[Matrota]

Stronghold Builder's Guidebook, page 25.

Short summary: a basic library (capacity: 2 lots) is 500gp, fancy library (3 lots) is 3,000gp, or luxury library (6 lots) is 15,000gp.

Filling the libraries with books costs 1,000gp per lot, if it's on a specific area of knowledge (+2 check to a specific kind of Knowledge check). You could also buy a lot of general books for 3,000 (+1 to all knowledge checks). Or you could buy a comprehensive book lot that takes up 3 lots and costs 5,000gp (+4 to a specific kind of knowledge check). Or a master book lot that costs 20,000gp and occupies 6 lots (+6 bonus to one kind of knowledge).

For your purposes, if you're cheapo, you could buy a basic library for 500gp and fill it with a lot of knowledge(arcana) books for 1,000gp and that would probably be enough.

You're a life saver, thank you!

[Jack_Simth]

In one of my current campaigns, my DM is permitting the custom spell creation rule, and there are a few spells I'd like to create for myself. Problem is, we're on a bit of a time crunch as our party is being hunted down by 3 other groups intent on taking some powerful artifacts we've obtained. And we're also after the enemy groups' artifacts. It's a big mess.

Anyways, I'm CL 23, and have access to the spell Genesis. My idea was to make my own private demiplane over the course of a week, make it timeless, and do my spell research/crafting there. Only issue is that I need access to a library as part of the rules for crafting a spell. I imagine with a few gates and plane shifts I could move a large horde of books into my private plane, and it would also serve as a nice place to astrally project myself from for safety. However, what constitutes as a library? How expensive would this likely be? Could I just purchase books over the subjects I'm intending to craft spells for for a more condensed and cheap "library?"
... timeless doesn't mean what you think it means. It doesn't mean time doesn't pass, just that spells don't expire and you don't get hungry/thirsty/old et cetera ... until you leave. If you're 23rd, though... just cast Time Stop when there. The spell won't expire, so you've got all the time you need that way.

[Matrota]

... timeless doesn't mean what you think it means. It doesn't mean time doesn't pass, just that spells don't expire and you don't get hungry/thirsty/old et cetera ... until you leave. If you're 23rd, though... just cast Time Stop when there. The spell won't expire, so you've got all the time you need that way.

Oh, okay. So a time stop would allow me to do all the research and spellcraft in a round of time while on a timeless plane? That's pretty handy.

[Jack_Simth]

Oh, okay. So a time stop would allow me to do all the research and spellcraft in a round of time while on a timeless plane? That's pretty handy.

Be ready for thrown DMG's.

[Matrota]

Be ready for thrown DMG's.

Are you implying there's a rule against this, or that my DM will probably be pissed off and actually throw stuff at me? (Ngl it is a pretty cheesy way of getting around time elements)

[PaucaTerrorem]

Are you implying there's a rule against this, or that my DM will probably be pissed off and actually throw stuff at me? (Ngl it is a pretty cheesy way of getting around time elements)

Depends on the GM. It's a bit cheesy but RAW legal AFAIK.

[Jack_Simth]

Are you implying there's a rule against this, or that my DM will probably be pissed off and actually throw stuff at me? (Ngl it is a pretty cheesy way of getting around time elements)
I'm not implying that there's a rule against it, just that it's too optimized for most gaming tables. See, you don't want one character at a gaming table significantly out of line with the optimization level of the others (up or down, doesn't matter). When you have that situation, the DM has an annoying choice: Send stuff at the party that will challenge the more powerful member(s) - and steamroll the less powerful member(s) - or send stuff at the party that will challenge the less powerful member(s) - and get steamrolled by the more powerful member(s). Neither choice is very good as a DM.

[Fizban]

Stronghold Builder's Guidebook, page 25.
Not quite. What you actually want is Tome and Blood, page 72. An Arcane Library costs at least 10,000gp and contains at least 200 books.

Oddly enough, Stronghold Builder's Guidebook has a Magical Laboratory (on page 27) which gives a bonus on spell research and is described as having "a small mystical library," but it doesn't actually say it allows the research in the first place. Tome and Blood is the only book that addressed the question specifically, though various setting books have places that are flagged as sufficient if you can get the owners to let you use their library.