The first thing we should try is the FLY spell. I mean, it's totally possible that he would love to be able to fly!

But before we cast it, we need to be prepared for what happens if he's not willing to fly.  In other words, he will be awake.  

But if he wants to fly, we're done. All we have to do is make him fly, right? 

If he doesn't want to fly then we have to be ready to take potions. Potion of invulnerability for each of us lasts 1 minute and makes us resistent to any damage.  And be prepared to cast Reverse Gravity while the fighters fight if he doesn't take flight willingly.

"First off, ideally, he shouldn't know we're there. We use some invisibility spell first on us and any summoned creatures. Then wake it, show it the image way up, then cast Fly, how about that? I can't emphasize enough how much we should not attack it unless all else fails."

So it seems the plan is:

- Cast Major Image to create an illusion of a flying tarrasque above the real one. There's no saving throw against this spell.
- Wake up the real tarrasque!
- Cast Fly on the tarrasque, hoping it will be willing to fly up to the fake tarrasque. Again, there is no need for it to make a saving throw, so legendary resistance and magic resistance won't apply.

- If that doesn't work, then create some other effect that prompts it to make saving throws, using up its Legendary Resistance. What is the role of the pixie? Normal attacks won't prompt saving throws, so be clear what is being attempted here.
- Once Legendary Resistance is used, then spam-cast True Polymorph and Reverse Gravity, until it fails a saving throw.
- Hope in the meantime that the tarrasque doesn't kill everyone and eat everything.

Does anyone have Bane or something similar? Would want to wear down the Legendary Resistance first, but if it fails the initial CHA save, then it might be more likely to fail the more important saves against True Polymorph or Reverse Gravity.

Also, I'd suggest Reverse Gravity may be better to start with, because as someone said, the tarrasque is so heavy that even if it grabbed on to anything, nothing would hold its weight.

Actually he doesn’t really use his sight so if he’s awake he will know where we are.  

i still think reverse gravity is the best spell to use on him. even if he was to save on a dexterity throw against our spell dc, there is absolutely nothing that will hold him down. He’s going to fly. 

we could use any simple spells to get him to use up his 3 auto saves. Spells like Toll the Dead. He has to make a dex save against my or the other spellcasters spell save dc. We could rapid fire save spells like that or create bonfire until he’s out of saves with our fighters distracting him with hopefully ranged weapons. 

There are spell scrolls. It doesn’t matter if you have reverse gravity or not as king as we’ve got spell scrolls. Any caster can use a spell scroll. It causes him to make a dex save, his worst nightmare. We only want to use spells that make him make dex saves. But he’s not just going to be sitting around waiting on us to beat him. He’s going to try to kill us. 

So we all have potions of psychic resistance to try not to be frightened and we all need potions of supreme healing. 

(( We're getting mired on details, so I'll go ahead and explain exactly what Onyx currently plans to do:

PHASE I

1. Cast Conjure Fey to summon a pixie (this will take ten rounds, so a full minute)

2. Head up to the roof/fifth floor with our scrolls and minions, including the pixie, but don't actually go onto the roof yet

3. Command the pixie to cast spells on the creature, while everyone else's minions do the same

4. Specifically, direct the pixie ahead of time, with instructions to do the following:
 - Upon entry to the roof, cast Fly on the creature
 - If the spell doesn't work, cast Polymorph on it
 - If THAT spell doesn't work, presume the creature is either awake or will awake, and continue flying around it as a distraction
 - If simply flying around it doesn't work, have it start using the Help action to assist anyone else attacking the creature

5. Drink any buffing potions, THEN actually go onto the roof

6. Let the minions do their thing, and goto Phase 2

PHASE II

1. Do one of two things:
 - If the creature immediately awakens, and is not docile, cast Greater Invisibility on one of our strongest fighters
 - Otherwise, cast Major Image of some sort of bait into the air (another tarrasque would be too big) to give it flying incentive

2. Cast Fly on the tarrasque himself, and direct Lannel to assist the fighters using the Help action to distract the creature as needed

3. If the spell doesn't work, drop concentration on prior spell and cast True Polymorph on the creature

4. If two rounds of casting by all spellcasters has failed, presume it's devolved into all-out battle and goto Phase 3.

PHASE III

1. Cast Banishment to try to buy everyone time

2. Upon the beast's return (or if the spell fails) fly to a safe distance

3. Try to survive! Keep attacking with Shatter and Eldritch Blast, drink healing potions as needed

So...

This seems like a sensible plan for him, and it should mesh just fine with whatever everyone else plans to do.  ))

(( EDIT: Yes, during discussions, Onyx secures a scroll of Banishment. ))

Quote from RodTheBard >>

 

 - Upon entry to the roof, cast Fly on the creature
 - If the spell doesn't work, cast Polymorph on it

 If the tarrasque is alseep, then it won't be a willing target for Fly, so perhaps leave that until it wakes up and has an incentive.

The pixie's Polymorph DC is 12, and the tarrasque has +9 WIS save, so there's a 1/10 chance of it failing, and if it does it will use Legendary Resistance. Would you rather cast unimportant spells first and get it to use up its saving throws?

I also notice that an unconscious creature "automatically fails Strength and Dexterity saving throws", so whether that is any help.

Quote from Crabitha >>

Actually he doesn’t really use his sight so if he’s awake he will know where we are.  

i still think reverse gravity is the best spell to use on him. even if he was to save on a dexterity throw against our spell dc, there is absolutely nothing that will hold him down. He’s going to fly. 

we could use any simple spells to get him to use up his 3 auto saves. Spells like Toll the Dead. He has to make a dex save against my or the other spellcasters spell save dc. We could rapid fire save spells like that or create bonfire until he’s out of saves with our fighters distracting him with hopefully ranged weapons. 

There are spell scrolls. It doesn’t matter if you have reverse gravity or not as king as we’ve got spell scrolls. Any caster can use a spell scroll. It causes him to make a dex save, his worst nightmare. We only want to use spells that make him make dex saves. But he’s not just going to be sitting around waiting on us to beat him. He’s going to try to kill us. 

So we all have potions of psychic resistance to try not to be frightened and we all need potions of supreme healing. 

 My problem with using Reverse Gravity is it's an attack. If it fails it is immediately going to be on attack and unwilling to go with anything else we may try. The only way to use Fly is to avoid attacking it off the bat. So I want to try the more peaceful method first.

Sorry for double post

“Onix, I like your enthusiasm for making a pixie do the work and all the work you’ve gone to using your imagination using illusions and so on but I think your plan disregards the Terrasque and its abilities. 
He doesn’t rely on his sense of sight much. He has Blindsight. 

As soon as it is awake, it uses its Frightful Presence ability and you or your pixie would need to make a wisdom saving throw of 17 not to be frightened. 

Then he bites with a +19 to hit. On a hit, all your hit points will be gone and you will be grappled. 
Next he attacks your pixie or anybody else with Horns, then Claws, then Tail, then Swallow. Each of his attacks will kill any of us. 

We can’t just keep hitting him until something works because we will all be dead. We have to use something on the first shot that has the very best chance of working. 

And that thing needs to be something he doesn’t have to make a wisdom throw to beat. 

if we are stealthy, and get a first round of attack off on him, our best chance against his defenses is something that requires him to use his dexterity. He is bad at it. And even if he somehow manages to save, it won’t matter. That is why reverse gravity will work.  He will be flying. 

"Will he be flying though? Is falling up really flying, or is it just falling? If it doesn't rely on sight and illusion won't trick it...cast Fly on me. It will be willing to fly to get to me, I will make sure of it," Hatch said.

We know Fly is flying. Reverse Gravity is debatable. If only Hatch is flying out of reach throwing things at it, and we get a stealthy summoned creature to cast Fly on it, the tarrasque will be willing to fly to reach Hatch and there's no is falling really flying question.

“I am also willing to fly and shoot at him from a safe distance (magic ammunition-bolts so that he feels them). I can attack from 120’ with no disadvantage (due to Sharpshooter feat), and I believe that he has no ranged attack except for his tail which is 10’. Assuming I hit him and he wakes, I think he will be very willing to fly to end my pathetic existence. But before he can reach me we should be freed from this trap. So the question is, is the fly spell by touch? If so, maybe a familiar that is very small can deliver it after his focus is on me?”

“Furthermore, if it wakes I can switch to my light crossbow and then move up to 320’ away to avoid its Frightful Presence (so no disadvantage), the only drawback is that switching to light crossbow reduces my attacks to 2 per round instead of 3 (ignoring reloading due to crossbow expert), but our goal isn’t to fight it to the death.”

(PS, my attacks are +11 up to the full range)

"So for my part: load up hand crossbow, have someone cast fly on me. The clock starts, I've got 10 minutes to get the Tarrasque in the air. I fly to where I'm 115' away from it. Fire 3 bolts from hand crossbow (+11 to hit each). Assuming I see him stir I use my 60' flying speed to retreat out of his possible Frightful Presence range of 120'. I continue firing and retreating, this time with my light crossbow (also +11, 2 per round) until he is airborne. The curse should end as soon as he lifts off. If it doesn't ... we're in trouble. Now, I will leave it up to the rest of you to figure out how to apply the fly spell to the Tarrasque." Throm is actually quite confident that this is going to work.

(It is critical that I get some magical ammunition - and that I get plenty of it to account for missing even with +11 against its 25 ac - or I doubt he will feel the bolts and thus not wake up)

“It would be fun if there was some way for me to magically sound like an amplified T-Rex, so there would be no doubt on the Tarrasque’s part where the damage was coming from.” Throm hopes that his magical partners can figure out how to do this from such long expected ranges.

Then a sudden dread crosses Throm’s face. “What if, even if the beast allows itself to be touched by an insignificant or undetected (in spite of blindsense) familiar, what if its low intelligence would keep it from ever considering trying to fly? This creature has been earthbound for millennia, so although it’s undoubtedly seen birds, would it even try to fly, even if it was suddenly capable?”

Quote from Crabitha >>

“if we are stealthy, and get a first round of attack off on him, our best chance against his defenses is something that requires him to use his dexterity. He is bad at it. And even if he somehow manages to save, it won’t matter. That is why reverse gravity will work.  He will be flying. 

"Of course. Which is why I expect someone capable of casting it to do so at the same time that I cast Fly," answered Onyx, somewhat confident, but even more excited now.

(( OOC: Same time meaning same round ))

Quote from CalvinHahnII >>

"So for my part: load up hand crossbow, have someone cast fly on me. The clock starts, I've got 10 minutes to get the Tarrasque in the air. I fly to where I'm 115' away from it. Fire 3 bolts from hand crossbow (+11 to hit each). Assuming I see him stir I use my 60' flying speed to retreat out of his possible Frightful Presence range of 120'. I continue firing and retreating, this time with my light crossbow (also +11, 2 per round) until he is airborne. The curse should end as soon as he lifts off. If it doesn't ... we're in trouble. Now, I will leave it up to the rest of you to figure out how to apply the fly spell to the Tarrasque."

"Hmm. I'd be willing to cast Fly on you, if this is a risk you want to take," said Onyx somewhat solemnly. "I can do so at the same time my summoned pixie is casting spells. She might wake him up in the process, so that should be even more to your liking. However, if I do, someone else will have to try casting Fly in case the other spells fail."

Quote from CalvinHahnII >>

“What if, even if the beast allows itself to be touched by an insignificant or undetected (in spite of blindsense) familiar, what if its low intelligence would keep it from ever considering trying to fly? This creature has been earthbound for millennia, so although it’s undoubtedly seen birds, would it even try to fly, even if it was suddenly capable?”

He shrugged. "Then the spell doesn't work, and maybe another will, or else we die trying."

"I think we can assume that whatever it's intelligence, it will know a spell has been cast on it. Worse case someone can use some kind of telepathy or something to make it realize it can. Besides, if the spell works on a willing creature maybe it won't need to intelligently know, maybe just wanting to fly will get it in the air. I don't have great range attacks, just a couple of handaxes, but I can use thaumaturgy to be loud enough to tick just about anything off."

Quin said, "I see I've been outvoted. I wish I could convince you to support my plan but I won't abandon you now. I guess we should proceed with Onyx's plan."

Perhaps you can have best of both plans. Casting Fly on the tarrasque requires it to be willing, and hence the idea of coaxing it into the air with illusions or attacks. Reverse Gravity puts it into the air, but is really just 'reverse falling' and not actually flying. If you Reverse Gravity then the tarrasque will already be in the air, and will presumably be a more willing recipient of Fly. It puts the airborne shooters in greater danger, but it might not matter once the objective is complete. Neither spell should require a saving throw from the tarrasque, so should be foolproof. Thoughts?