Cerlinde’s even more excited about the books than the stars.  She stows the familiar volume (making note of the letter) and then (perhaps rashly) peruses the other books with help..

17 investigation. 

Ollezall begins chanting the ritual for detect magic.

As he does so, Ollezall will peruse the stacks and look for anything that is not a book (or not truly a book) on the shelf.

Perception 22

"Chained books in a mansion where no other books are chained. Let's all be careful; the monks at my sanctuary kept books on necromancy chained to the walls, and behind guard. Dangerous books get chained"

Syd will help the others to examine the contents of the chained library, ostensibly looking for clues, and surreptitiously looking for... well, you know.

In her excitement over the prospect of even more arcane knowledge, Cerlinde rushes toward the bookshelf, first picking up the Mordenkainen-adorned tome featuring the letter 'L' on its spine, and then beginning to reach for what appear to be the most fascinating volumes.

Ollezall approaches with more caution, given his previous experience in the sanctuary.  As he reaches the bookshelf, with his excellent observational powers, Ollezall's fears are proven justified as he notices the chains of the shelf start to quiver.  As he calls out in warning, two books fling forward from the bookshelf, lashing out at each of our studious casters.  The books remain attached to the bookshelf by their chains, which are about 5' in length.

Animated Chained Library - attack vs. Cerlinde: 16, damage (bludgeoning): 10
Animated Chained Library - attack vs. Ollezall: 19, damage (bludgeoning): 5

(If either of you are hit, you are Grappled, escape DC 12.  Syd, you're in range to attack, help, etc., as you like.)

Hearing the noise, Dyumi stops looking at the stars and rushes in to help, casting Hex (STR) on the shelf and attempting to swat away some books with his staff.

Attack:10 Damage: 12 Magical Bludgeoning + 1 Necrotic

Syd quickly retrieves his new greatsword, and because why not, says "Shirak!"

He takes aim at the animated book grappling Cerlinde, and attempts to redact the hell out of it.  (Attack and damage rolled assuming there is no magical bonus to sword.)

Greatsword Attack: 14 Damage: 13 slashing

Quote from EtyenAndiros >>

In her excitement over the prospect of even more arcane knowledge, Cerlinde rushes toward the bookshelf, first picking up the Mordenkainen-adorned tome featuring the letter 'L' on its spine, and then beginning to reach for what appear to be the most fascinating volumes.

Ollezall approaches with more caution, given his previous experience in the sanctuary.  As he reaches the bookshelf, with his excellent observational powers, Ollezall's fears are proven justified as he notices the chains of the shelf start to quiver.  As he calls out in warning, two books fling forward from the bookshelf, lashing out at each of our studious casters.  The books remain attached to the bookshelf by their chains, which are about 5' in length.

Animated Chained Library - attack vs. Cerlinde: 16, damage (bludgeoning): 10
Animated Chained Library - attack vs. Ollezall: 19, damage (bludgeoning): 5

(If either of you are hit, you are Grappled, escape DC 12.  Syd, you're in range to attack, help, etc., as you like.)

 Reminding Ollezall of getting clout with a book by his instructors, Ollezall has the sense knocked out of him briefly; as Ollezall recovers, he feels the chains wrap around him. There is no way I break these through strength Ollezall thinks; Ollezall will take a few deep breaths in and while exhaling, attempt to slip out of the chains.

Dex save 9

Cerlinde reacts quickly, casting shield, causing the chains to miss.

she then casts fire bolt 21 to hit, and 10 damage 

Plus 4 crit damage :) 

(Oof, lots to go through here and you guys really walloped this thing.  Last party that I played this with, one got knocked out immediately and the rest retreated.  Anyway, here we go.)

(Dyumi, it's definitely been a minute since you last cast Shillelagh, so you have to pick either that or Hex for your BA.  I'll assume the former for now, since while the extra damage from Hex is nice, the disadvantage for STR - good thinking given the grappling - doesn't apply for this creature as written since their stat block just says DC 12 check to escape grapple, no opposing Athletics by the monster.  I don't know why.  So your attack will hit w/the rolled damage, just not the necrotic.  As usual, if I've misinterpreted this, please let me know!)
Dyumi looks like he must have spent some at least some time studying Fistandia's combat diagrams in the exercise room as he expertly spins and delivers a powerful strike with his enchanted quarterstaff.  The chains appear... rattled.

Syd lights up that magnificent sword (you're right, no bonuses, but magical for purposes of resistance) and takes a hack at a chain lashing out at his friends.  Being unaccustomed to attacking with a glowing blade, he nearly misses, but his brute strength, skill, and enthusiasm combine to make for some healthy damage.  The book he struck is now flooded with black ink and barely legible.

(Ollezall, I looked at your DEX save and thought, he could have went with Athletics or Acrobatics, but when I looked at your sheet, every possible applicable thing for STR or DEX was exactly the same roll, so... nevermind.)
Ollezall's meditative escape technique seems promising, but his last exhalation is a sigh as he finds that he is still grappled.  Fortunately, his friends are beating the snot out of these chains and a dead foe cannot maintain a grapple.

Cerlinde, battle hardened from kobold encounters, knows just when to deploy that Shield and avoids a powerful strike.  Having learned from Fistandia's exercises, she responds with an even more devastating Fire Bolt, igniting the book that had just attempted to give her a lesson in pain.

(assuming the need of Round 2)

In an effort to demonstrate that the sword is in fact mightier than the pen, Syd becomes a censor, banishing offending books to the rubbish heap.

Greatsword Attack: 23 Damage: 13 slashing

Ollezall draws a dart from his pocket and stabs the most tattered book. "You mustn't push too hard with your quill Ollezall! You might tear the page!!"

Dart attack:

Attack 24

Damage: 4

Plus crit:  4

Cerlinde says “I think we err.. killed it?”  She sadly examines the burned book, hoping it’s a  smutty novel and not something more valuable.   If the library is still moving she will blast it again.  

Assuming combat is over she searches to see what books are present..

(Yeah, that'll do it for the animated chain library.  You are rolling like you've hacked DDB's systems!  ;-)

With Syd's censorship and Ollezall's critical dart stabs, the animation ceases and you are left with a stationary chained library.  The party can now safely resume reviewing Fistandia's secret stash.  There are rare tomes on the sciences, arcana, and alchemy, as well as books about planar lore and the summoning of fantastic creatures.  All the books are firmly affixed to the shelves by enchanted chains and you don't see any way to release them.

However, there is one book that was freed from the shelves during combat, the slightly crisp volume that was toasted by Cerlinde's Fire Bolt.  With the chain still attached, you get the feeling that this might make a pretty good flail, maybe even a special one.  The title of the book is "Martial Attack Techniques".

Dyumi will pick up the fallen book, swing it around a bit, and then put it back down. He could probably deal some nice damage with it, but he prefers his staff. Perhaps someone else could use it more effectively.

(For the record, Dyumi will be constantly be keeping Shillelagh up while out of combat)

Cerlinde will inventory the books that are present, in particular to see if any might help with Haven’s dimensional stability issues.  (She makes a list of the books on the map she’s been drawing of the mansion) .  She also checks to see if any contain spells.   

Once it becomes clear that there is no smut to be had in the library, Syd will investigate the rest of the room.

Waking up from the PTSD episode of Ollezall's penmanship class, Ollezall touches each party member appropriately and casts guidance. 

"Dyumi, that book flail looks sick. I wouldn't have thought firbolg were skilled in using such weapons of war. My instructors always described Firbolg as peaceful stewards of the trees.....though they also warned us severely to stay away from any forest a Firbolg was keeping; perhaps I know why now"

(Sorry for the delay, yesterday was an extremely hectic day and just passed out at some point.)

Quote from Great_Axeblade >>

(For the record, Dyumi will be constantly be keeping Shillelagh up while out of combat)

(I probably spent far too much time thinking about the mechanics of this, both from a "realistic" and a game rules perspective, but here's what I've settled on.  Let me know if this seems fair, crazy, or something in between.  Assuming that, for some IC reason, Dyumi has developed the borderline OCD habit of always clutching his staff and casting the same spell every minute, e.g., he was jumped and nearly killed in one or more encounters, one would still have to make at least one assumption.  Since the passage of time out of combat is pretty nebulous, we have to assume that a variable amount of time has passed between the last casting and the start of combat.  In order to accommodate that reality, what I propose is that if you don't explicitly state you're using Shillelagh prior to combat, you can roll a 1d6 to determine how many remaining rounds of Shillelagh you have before you need to use a BA to recast.  For example, this would happen when you are surprised, like w/the last encounter, or if Dyumi happened to have been absentminded or occupied in the last minute, which I think could be IC for him.  For the purposes of this adventure, there's not too much fighting left to do, so it might not come up, but like I said, everyone can give me some feedback on this idea.)

Quote from Tesservett >>

Cerlinde will inventory the books that are present, in particular to see if any might help with Haven’s dimensional stability issues.  (She makes a list of the books on the map she’s been drawing of the mansion) .  She also checks to see if any contain spells.   

Cerlinde finds 3 books that look particularly useful in solving Haven's portal problem.  Most prominently, she's identified one, "Plane and Simple: A Practical Guide to Placating Portals", that seems to hold great potential.  There are 2 spell books, but it will take some time (and checks) to determine the contents, if she is able.

Quote from Syd_Wartnose >>

Once it becomes clear that there is no smut to be had in the library, Syd will investigate the rest of the room.

Syd doesn't find any smut amongst the books, but he does notice that the wood plank ceiling above the room appears to not be particularly strong.

Quote from Potaido_ >>

Waking up from the PTSD episode of Ollezall's penmanship class, Ollezall touches each party member appropriately and casts guidance. 

"Dyumi, that book flail looks sick. I wouldn't have thought firbolg were skilled in using such weapons of war. My instructors always described Firbolg as peaceful stewards of the trees.....though they also warned us severely to stay away from any forest a Firbolg was keeping; perhaps I know why now"

(Sick as ill or sick as in siiiiicccckkk / gnarly / rad ?  ;-)

(not particularly strong as in... About to collapse on us? Or as in there might be a hidden trapdoor?)

Quote from Syd_Wartnose >>

(not particularly strong as in... About to collapse on us? Or as in there might be a hidden trapdoor?)

 The latter.