Quin sees Throm  and Galerius when they comes in. She shows him the book she found with information on the Tarrasque, and says, "I think it's simple." 

But only if someone has the spell, "Glyph of Warding."  All we would have to do is make a glyph of warding that is set to go off when the Tarrasque makes any movement. Store a level 3 spell in the glyph of warding. The level 3 spell being "Fly."

I have the Fly spell but we need somebody who has Glyph of Warding.  To set up the Glyph of Warding, it would help if we have someone who has the "Heroism" spell. Whoever is setting up the Glyph of Warding could have that cast on them to protect them from being frightened. But hopefully the person who sets up the warding would be very stealthy and quiet but if not, perhaps we could distract the Titan in some other way.

Buck is doing recon to see if there are any other guests in the castle with magic abilities. If none of us has Glyph of Warding, perhaps someone else will.

Well, that's my idea so far. The Fly spell touches one willing creature. I don't think the Tarrasque would unwilling to fly. I think the Tarrasque would love to be able to fly. We would just have to get the hell out of the way before the warding glyph goes off. If he goes flying, it's probably going to bring this tower down and maybe even the fourth floor.

“Perhaps the book will tell us how the Tarrasque came to rest on the top of a castle. Surely it didn’t walk up there. Either someone teleported or levitated the sleeping monstrosity, or the castle was built below it while it slept”, muses Throm out loud.

Hatch thanks Willagee and heads off looking for the others, eventually coming to the library. Having missed Quin's plan he was not able to find anything to say. He was pretty sure that he couldn't do much in this situation.

(Do we absolutely need Glyph of Warding for the Fly spell to work?)

Throm suggests everyone search their memories for any historical, religious, or magical recollections of anything having to do with the Tarrasque. Time to pull out all the stops. Also, searching through all of the tomes in the library for any documentation on who/how it got to be on the roof without destroying everything to get there.

History: 17
Religion: 7
Arcana: 15

Investigation: 0

(Ha, curse my dullard blockhead)

Galerius searched through the books, looking for the Glyph of Warding and information on the tarrasque.

History: 19

Arcana:17

"Hold up.", says Galerius softly. "What's this?"

He uncovers a book written in Draconic. Its name is wer waphir habitats di wer tarrasque.

Translated it reads as so: The Living Habitats of the Tarrasque.

"It's an interesting plan," says Onyx, leaning on a shelf within the library, and with his owl perched on his shoulder. Apparently he had found his way down shortly after Lannel's visit to the top of the castle.

"But I don't know that putting the spell into a glyph would add much. The spell wouldn't change, except to relieve us of the burden of concentration; the creature's willingness would still be a factor. Perhaps charming it first would work? But then it might consider that a threat, and resist the spell. Vehemently, at that."

He stepped forward as he began looking through the books while still speaking.

"All that aside, I had Lannel fly up to check out the creature. It's there alright, larger than life, but it seems to be in a strangely deep sleep. Magical, perhaps? We might not have any trouble actually getting to the monster, but I wouldn't want to be the one speculating on what might accidentally awaken it."

(( OOC: Checks for Onyx to find something useful while digging through the library:

Perception Check: 21
Investigation Check: 23

Also, checks for knowledge of the tarrasque:

History Check: 14
Arcana Check: 22 ))

"Hmm. While we're here... I don't suppose anyone knows or knows of the Telekinesis spell?" (( OOC: He's wondering if it's in anyone's class spell list ))

(( EDIT: Forgot Onyx had Guidance! He'll be using it liberally here, and offering it to the others; Galerius and Throm can, if they wish, add 1d4 to each of their skill checks in the library. So can everyone else, BTW. Onyx will add the following rolls to each of his four checks, in order: 4 3 4 4 ))

Galerius read aloud from  The Living Habits of the Tarrasque:

[Translated]: The Tarrasque engages in slumbers lasting hundreds of years. It is often found atop the peaks of mountains or other structures. Tarrasques have great constitution and strength but are weak in both wisdom and intelligence. As such, a tarrasque is greatly vulnerable to arcana.

Lok leaves his room in search of the others, hoping to be caught up on any information they found while he was resting. 

(Unfortunately, Lok has zero knowledge on anything magical, so he will not be able to help with any of that)

"I say, Onyx, have you found anything?"

(( OOC: Well, both Onyx and I are personally not very knowledgeable about tarrasques. That's why, with this character, I'd prefer to wait until the DM reveals what I've come across based on my rolls. Hopefully Onyx will get to answer shortly. ))

Quin points to the book she found with references to the Tarrasque and says, “The tarrasque is impervious to being charmed.” Orifially I had thought casting ‘Awaken’ on it as that would make it a willing creature. But unfortunately he cannot be charmed. Awaken would have been perfect as it targets creatures of less than 4 in intelligence.”

she looks at Hatch and says, “We could certainly try the Fly spell without Glyph of Warding but I’m afraid the caster might not survive.”

“I seem to remember that Kardinyia was described as magical some time ago. I find that Bentley has a wand. It’s possible that Willagee has magic of some sort too.”

“If Buck can ferret out anything about the staff or other guests that might have magic that could prove useful, I should know when he returns.”

“To defeat the tarrasque without magic would take an army. So I’ve been thinking of spells that are of potential use. Here’s a list: 

Heroism: Provides immunity to frightened condition. 
Enlarge/Reduce: Make him smaller by half.

pass without trace mskes everybody stealthier. 
Rope Trick: dangles a rope we could climb up and be out of harm’s way trmporarily.

Web: bind him while he’s asleep maybe.

“Lok, my best friend was a Barbarian. She used to tell me her brain want much use but she was the smartest person I ever met. You don’t have to have magic to come up with ideas. Ideas are what we need.”

lia quickly showed the information about the Tarrasque to Hatch and the others. 

Galerius listened to Quin, nodding in assent.

I have an Idea. The riddle says "Five flies", but maybe, just maybe, floating in the Astral Plane would count. Just a suggestion. I am unsure if planar warps are even possible here.

Galerius headed down to the first floor.

Willagee? Is planar transport possible here?

Lia nods, considering everybody's ideas. She thinks back to her studies on schools of magic, and an idea hits her like a mace to the head. "What about some kind of Transmutation spell? We could try to turn the Tarrasque into some kind of winged creature, preferably something small, like an insect. It couldn't be too hard to get it to take off after that... I mean, surely it'd be smart enough to work out it's new wings? Especially if it decides to try and chase us." She pauses, thinking. "That would take a fairly adept spellcaster..."

(The spell I'm thinking: Polymorph. It's a level 4 spell, and with 9 levels of Bard (Onyx, hopefully.) you should be able to learn it, or forget another spell to learn it. If we decide to go with it, that is. Plus it's a Wisdom saving throw, so we might struggle to have the Tarrasque fail the throw. Just tossing some ideas around.)