Killing Tiamat inside a Forcecage

[Eldariel]

B is flat out false (or at least not determined). You can't say "well, gargantuan is 20x20, so she fits". Gargantuan is 20x20+. It's unbounded on the upper end. Ships are gargantuan and have sizes larger than 20x20. So you can't claim that all gargantuan things are 20x20. Which is what it takes to say that by the book she fits. Size category is not physical size, and physical size is what matters for the spell.

Gargantuan is 20'+ and if it doesn't say anything beyond that, it defaults to 20'. That's the point. The monsters (e.g. Tarrasque) that are bigger say so. She doesn't. Size category is what space she takes on the grid and thus where she'd fit. Else DM can't know how to run them other than "wing it". There has to be a default and in an half-open group, the only defined number is the lower bound.

[Dork_Forge]

B) By the books she does fit in there. This is an issue you'll have to take up with the writers.

As PhoenixPhyre pointed out, this is just not true. It's like arguing a mouse and a cat can both fit inside your small belt pouch because th they're both tiny. There's just a finite number of siza categories, it is what it is, which is open ended on the far end.

@Dork_Forge: FWIW I made a StackExchange question about the ruling and the consensus is about what you'd expect: DM call. Though I would, by parallel to magic weapons (which work just fine) and spell that make weapons magic weapons (Magic Weapon, Holy Weapon, Elemental Weapon) argue that the too damage is self-facing effect and thus not subject to magic immunity. And as advantage isn't gained vs. any specific enemy but all attacks in general, I'd definitely argue it's more akin to Samurai's Fighting Spirit than an enemy-applying effect like Hex or Hexblade's Curse.

I've also seen StackExchange (and I think here) backing that weapons made magical by spells wouldn't cut it, backed by JC tweets so... eh?

Thinking about the advantage I'm leaning on yes just because of how things like Guiding Bolt work, but in no way can I see the extra damage not being a spell effecting her.

It's like casting a Smite spell and saying well, the spell doesn't actually damage the target directly. It's additional damage that comes directly from a spell, if it was something like you gain a +2 to Str then sure, it's an indirect damage buff, but this isn't that.

Gargantuan is 20'+ and if it doesn't say anything beyond that, it defaults to 20'. That's the point. The monsters (e.g. Tarrasque) that are bigger say so. She doesn't. Size category is what space she takes on the grid and thus where she'd fit. Else DM can't know how to run them other than "wing it". There has to be a default and in an half-open group, the only defined number is the lower bound.

Is there actual a written rule somewhere that says it defaults? Or are you just assuming because some blocks include the size ,I think all should but that isn't a reason to conclude if it doesn't everything defaults.

[Eldariel]

As PhoenixPhyre pointed out, this is just not true. It's like arguing a mouse and a cat can both fit inside your small belt pouch because th they're both tiny. There's just a finite number of siza categories, it is what it is, which is open ended on the far end.

When you have a book that says "Gargantuan" and fails to specify size beyond that, any number but the "X" in "X or larger" is arbitrary and thus DM fiat.

[Dork_Forge]

When you have a book that says "Gargantuan" and fails to specify size beyond that, any number but the "X" in "X or larger" is arbitrary and thus DM fiat.

That is not the same thing as defaulting to the smallest size, it's an edition that built itself upon DM rulings.

Heck, just look at the portal she comes out of, I just mapped out a 20x20 and it was insignificantly small in the middle. Whilst it doesn't say the exact size, it's readily apparent it isn't meant to be the Force Cage convenient default...

Fun thought exercise, if she's the smallest possible size, where is she meant to come out of the portal where she could actually do anything (and the party has a decent chance of doing anything to her)?

[CapnWildefyr]

She doesn't have Wish, far as I can see.

I do not own the module, so I looked online. The stats blocks I saw there for her avatar show wish as a spell for the red dragon head, so that's what I was going by. (Wonder which stat block is newer, or if the one is "dumbed down"? )

That is not the same thing as defaulting to the smallest size, it's an edition that built itself upon DM rulings.

Heck, just look at the portal she comes out of, I just mapped out a 20x20 and it was insignificantly small in the middle. Whilst it doesn't say the exact size, it's readily apparent it isn't meant to be the Force Cage convenient default...

Fun thought exercise, if she's the smallest possible size, where is she meant to come out of the portal where she could actually do anything (and the party has a decent chance of doing anything to her)?

Yes. Gargantuan is 20 x 20 or larger. I agree, you cannot just say anything gargantuan fits into a 20 x 20. Yes, a DM has to make a decision. Yes different DMs will come up with different numbers. They should at least have given rough dragon sizes like they used to do. [FWIW I recall stats like an ancient red was maybe 300 feet + tail?? Might be misremembering. I once has the satisfaction of plunking a foot long dragon fig down onto a battlesystem map and saying, 'that's to scale.']

If you assume something of gargantuan size defaults down, it leads to some absurd possibilities. For example, why not pole vault a mountain? If nothing in the module says how big the mountain actually is, it must fit into a 20x20 square! Of course, we all "know" how big mountains are, but if the module doesn't specify it exactly...

I guess you can say "well, I decide 20 feet long" but that's kinda tiny for a dragon goddess... unless maybe pseudodragon goddess...

[Waazraath]

Yes. Gargantuan is 20 x 20 or larger. I agree, you cannot just say anything gargantuan fits into a 20 x 20. Yes, a DM has to make a decision. Yes different DMs will come up with different numbers. They should at least have given rough dragon sizes like they used to do. [FWIW I recall stats like an ancient red was maybe 300 feet + tail?? Might be misremembering. I once has the satisfaction of plunking a foot long dragon fig down onto a battlesystem map and saying, 'that's to scale.']

If you assume something of gargantuan size defaults down, it leads to some absurd possibilities. For example, why not pole vault a mountain? If nothing in the module says how big the mountain actually is, it must fit into a 20x20 square! Of course, we all "know" how big mountains are, but if the module doesn't specify it exactly...

I guess you can say "well, I decide 20 feet long" but that's kinda tiny for a dragon goddess... unless maybe pseudodragon goddess...

If you look at earlier editions a guargatuan red dragon had an overall length of 85 ft, a colossal one 120 ft... (3.5 Draconomicon). Yeah, I know, other edition other game and all that, but for context, I think it's telling, added up with the artwork, the size of the portal, the whole idea that the goddess of dragons is supposed to be bigger than normal dragons, etc. etc.

[CapnWildefyr]

If you look at earlier editions a guargatuan red dragon had an overall length of 85 ft, a colossal one 120 ft... (3.5 Draconomicon). Yeah, I know, other edition other game and all that, but for context, I think it's telling, added up with the artwork, the size of the portal, the whole idea that the goddess of dragons is supposed to be bigger than normal dragons, etc. etc.

Yep. The thing is, even at minimum gargantuan size, if a creature is anywhere near 20 long or wide or tall, it should get a save vs being trapped, and in Big T's case, she's got a big bonus and does she also get advantage?

One fighting tip that popped into mind -- what about illusions of 1 or 2 beholders. Beholders, with that big anti-magic ray, could be a bother to Tiamat... she might focus on them for a few rounds, if she believes the illusions, letting others get in a few good shots.

[Dork_Forge]

Yep. The thing is, even at minimum gargantuan size, if a creature is anywhere near 20 long or wide or tall, it should get a save vs being trapped, and in Big T's case, she's got a big bonus and does she also get advantage?

One fighting tip that popped into mind -- what about illusions of 1 or 2 beholders. Beholders, with that big anti-magic ray, could be a bother to Tiamat... she might focus on them for a few rounds, if she believes the illusions, letting others get in a few good shots.

I'm not sure why she'd be bothered by Beholders really, but she has Truesight so there's no real chance of tricking her with an illusion.

Forcecage would only proc a save if she tried to teleport out of it, I don't really understand the point of the spell tbh.

[Eldariel]

That is not the same thing as defaulting to the smallest size, it's an edition that built itself upon DM rulings.

Heck, just look at the portal she comes out of, I just mapped out a 20x20 and it was insignificantly small in the middle. Whilst it doesn't say the exact size, it's readily apparent it isn't meant to be the Force Cage convenient default...

Fun thought exercise, if she's the smallest possible size, where is she meant to come out of the portal where she could actually do anything (and the party has a decent chance of doing anything to her)?

Well, the Great Apse is about 120' across but nothing suggests the portal is that size. It could easily be a 40'/40' portal, which is just fine for a 20'/20' creature.

As for 3e comparison, 5e is struck by a curious case of creature miniaturism where few creatures are truly all that big. Surely it's reasonable to say that the board size means nothing or that the creature takes an arbitrary number of squares but there's little in the game supporting that outside few specific creatures.

[Dork_Forge]

Well, the Great Apse is about 120' across but nothing suggests the portal is that size. It could easily be a 40'/40' portal, which is just fine for a 20'/20' creature.

As for 3e comparison, 5e is struck by a curious case of creature miniaturism where few creatures are truly all that big. Surely it's reasonable to say that the board size means nothing or that the creature takes an arbitrary number of squares but there's little in the game supporting that outside few specific creatures.

If she's that small then the encounter is just weird.

I mean come on, are you really arguing that you think she's that small or is the a rules quibble?

Just look at the cover of the book, there's a medium creature right there for size reference:



Doees that really look like 20x20 to you? Those are just her heads, not even her whole body.

[PhoenixPhyre]

Well, the Great Apse is about 120' across but nothing suggests the portal is that size. It could easily be a 40'/40' portal, which is just fine for a 20'/20' creature.

As for 3e comparison, 5e is struck by a curious case of creature miniaturism where few creatures are truly all that big. Surely it's reasonable to say that the board size means nothing or that the creature takes an arbitrary number of squares but there's little in the game supporting that outside few specific creatures.

You're still thinking in grid terms. Grids are explicitly a variant rule. So that whole thing about being 20x20 unless specified otherwise? Yeah. That's not a system assumption. Gargantuan creatures

a) control at least a 20x20 region.
b) have indeterminate size
c) several of them are noted (in the description but not the stat block) as being substantially larger.
d) usually have minis that are way bigger than 20x20 physically, despite being on a 20x20 base. I have an ancient blue dragon mini (official) that has a wingspan of ~100' to scale. And blues aren't even the biggest dragons.
e) are big enough that a hostile Large creature (usually 8+ ft tall) can walk underneath one with only difficult terrain. That puts their bodies at 8-10' off the ground at the bottom.

Krakens explicitly have a 30' reach. That means 30' tentacles at a minimum.

Giants are huge, but most of them are taller than 20' explicitly. Size category =/= space occupied. And forcecage only cares about the latter, not the former. We have spells that refer to size categories. They do so explicitly. Forcecage does not. So it must be referring to physical size. So you're not catching a giant in a forcecage either. And what you can is up to the DM.

[MaxWilson]

I meant how many squares would she be on a grid, I know it's a variant rule technically, but it's the most convenient way of tracking distances and positioning.

She has five heads, does that effect your size recommendation?

I've never heard of any of those things, but from what I know of Spelljammer, it certainly tracks!

150 yards x 50 yards is 90 squares by 30 squares, so that's what I'd use.

Five heads is why I made her 50 yards wye instead of 30--needs more shoulder room and torso width to support the extra heads.

Krakens explicitly have a 30' reach. That means 30' tentacles at a minimum.

Not a minimum. Humans have 5' reach on punches, but not 5' long arms. Reach apparently includes (the possibility of) some movement.

[Dork_Forge]

150 yards x 50 yards is 90 squares by 30 squares, so that's what I'd use.

Five heads is why I made her 50 yards wye instead of 30--needs more shoulder room and torso width to support the extra heads.

Thanks for the recommendation, I'll go with that.

I was clarifying because in the post I replied to you said she had three heads, so was just making sure.

[PhoenixPhyre]

Not a minimum. Humans have 5' reach on punches, but not 5' long arms. Reach apparently includes (the possibility of) some movement.

Ok. So say 27.5' tentacles. Because otherwise you'd have to move enough to end up in another square. But either way, body + tentacles >> 20'.

[Dork_Forge]

I made the thread for testing the statblock, for accuracy of the statblock any context of the module itself is ignored. Thread here all welcome to run a proposed party through or make any suggestions about the scenario.

[MaxWilson]

Thanks for the recommendation, I'll go with that.

I was clarifying because in the post I replied to you said she had three heads, so was just making sure.

Oh! I see. I don't know how my fingers typed "three" instead of five. That's strange, but not the strangest typo I've ever made. Thanks for clarifying.

I wasn't recommending per se, just stating my own preference/imagination, but am glad you found it useful.

[Dork_Forge]

Well the results of the first attempt appear inconclusive.

My offer stands for anyone that would like to take it.

[N7Paladin]

Well the results of the first attempt appear inconclusive.

I've been following this for a while. I read the test. It was must certainly not inconclusive.

{Scrubbed}

[Eldariel]

I've been following this for a while. I read the test. It was must certainly not inconclusive.
{Scrub the post, scrub the quote}

Considering I specifically conceded every single point we discussed:
- Diviner Simulacrum not regaining Portent
- Magic Jar (I simply agreed to not use it in spite of it being a 6th level spell and excellent for these characters)
- No magic items
- Only 7th level+ buffs working on weapons dealing full damage
- Going PHB only
- Ignored the obvious terrain
- Gave her whatever dimensions desired (even though the original point was that she goes down to Forcecage by RAW, so this makes for a whole different discussion)
- Removed context from the challenge in spite of the context of her appearance making her much weaker

And then had a disagreement that had nothing to do with how the test itself goes (specifically about readied actions that I didn't want to waste time asking about since I assumed Dork_Forge would understand what I mean and would want an efficient run for what amounts to a test of mechanical strength, not actual play), where Dork's ruling would obviously result in the test being invalid since it's got nothing to do with party and everything to do with player-DM miscommunication, this seems very surprising to me. I have a hard time understanding the amount of vitriol I see in this post, unless you feel somebody you care about has been personally insulted.

This phenomenon seems to occur more broadly though: it is actually very surprising to me that calling Tiamat a chump seems to be raising emotions. Is criticizing monster statblocks really such a sensitive topic? In your post specifically, I notice how you even highlight Goddess Tiamat and calling the given statblock a chump to be somehow negative. That's not at all my goal: I want to give her the statblock she deserves. And the statblock she was given (same with many other 5e monsters, Tarrasque of course being the easiest example) simply doesn't match up. I'll probably end up showing you that a level 14 party can kill her (even though that isn't at all required for her to be a chump - a CR30 creature should be able to beat a level 14 party effortlessly), but of course you can take what you will out of that.

Still, I plead that you at least don't equate me studying a point (e.g. in this point whether a party can kill a monster by RAW) to me playing the game. That's a massive disservice. Not that there's any need for us to ever play with each other, but I'd still rather you don't you presume such amount of knowledge without ever interacting with me personally.

[JNAProductions]

If Tiamat is really such a chump, one thing going wrong shouldn't matter much, right?

[Eldariel]

If Tiamat is really such a chump, one thing going wrong shouldn't matter much, right?

When you're playing a level 14 no magic items core only party banned from using certain spells with no prep at 60' starting distance in an arena she shouldn't even really be able to move in, you have far less margin for error than if you were running it normally... Again, there's more it takes for a CR30 God to be decent than beating a level 14 party with a lot of stipulations and a DM misinterpretation. It might be winnable after that but I'm simply not interested in "btw, you worded this wrong so take 96 damage to the whole party after I randomly force you to start at 60' and in Fireball formation in an unbounded fight" - that's so far from the original point of the thread it's not even funny.

{Scrubbed}

[Dork_Forge]

Considering I specifically conceded every single point we discussed:

Okay, let's discuss why you're painting this very one sidedly, despite the fact that the party you chose was up to you and had allowances that highly favoured you.

- Diviner Simulacrum not regaining Portent

Worst case scenario here, oh no you don't have a maximum of 6 portents! But this is also something I mentioned but did not make a ruling on, I explicitly left it up to you to avoid seeming biased against your proposed outcome. BTW I was under the impression that the Simulacrum was going into it with all portents available.

- Magic Jar (I simply agreed to not use it in spite of it being a 6th level spell and excellent for these characters)

Boohoo you didn't get to grab stronger monster bodies for the PCs? Magic Jar is campaign dependent and neither of us had interest in playing the module out, assuming you could esily grab multiple bodies is not particularly reasonable towards proving your claim.

- No magic items

You chose this, I offered every character a +1 weapon.

- Only 7th level+ buffs working on weapons dealing full damage

A reasonable interpretation backed by posts on a website you made a post on yourself trying to prove a point (oh and also a tweet by JC)

- Going PHB only

Don't say that this was a point brought up, this was entirely your own decision. People speculated that you originally chose a party that was heavily composed of post RoT materials. I said nothing regarding you not using anything and was surprised when you elected to.

- Ignored the obvious terrain

What?

- Gave her whatever dimensions desired (even though the original point was that she goes down to Forcecage by RAW, so this makes for a whole different discussion)

Gargantuan defaulting to the smallest size is not RAW, that's your opinion and to avoid bias i sourced a size from a 3rd party publicly in this thread.

- Removed context from the challenge in spite of the context of her appearance making her much weaker

Lol whut? Is this about the optional ways to weaken her where you decided the minute beforehand would be just sitting around whilst the priests conveniently ignored the party?

You blanketly labeled the statblock as a chump, fighting the statblock at full strength should not have been an issue but rather the point of the exercise. If you issue was the encounter design, which at no point did it seem to be, that's entirely separate and all to do with the party meant to have a meaningful way to interact with the game and try to win.

And then had a disagreement that had nothing to do with how the test itself goes (specifically about readied actions that I didn't want to waste time asking about since I assumed Dork_Forge would understand what I mean and would want an efficient run for what amounts to a test of mechanical strength, not actual play), where Dork's ruling would obviously result in the test being invalid since it's got nothing to do with party and everything to do with player-DM miscommunication, this seems very surprising to me. I have a hard time understanding the amount of vitriol I see in this post, unless you feel somebody you care about has been personally insulted.

Yeah, no. You assumed you could do something that isn't RAW nevermind RAI or a ruling I would make, you got it wrong and didn't like when I didn't let you have a do-over. I didn't allow such a thing because the action taken seemed reasonable and still had value in the situation. You assuming things is not efficient, it's the opposite since it's more likely to either 1)cause arguments after the fact (like the one you stormed off from) and 2) leads to you making favourable assumptions that do not relect RAW nevermind reality. Once more with feeling, not my ruling it's literally RAW and it's not my problem that you chose to assign your party names and genders in a simulation but couldn't be bother to be specific about a mechanical trigger.

This phenomenon seems to occur more broadly though: it is actually very surprising to me that calling Tiamat a chump seems to be raising emotions. Is criticizing monster statblocks really such a sensitive topic? In your post specifically, I notice how you even highlight Goddess Tiamat and calling the given statblock a chump to be somehow negative. That's not at all my goal: I want to give her the statblock she deserves. And the statblock she was given (same with many other 5e monsters, Tarrasque of course being the easiest example) simply doesn't match up. I'll probably end up showing you that a level 14 party can kill her (even though that isn't at all required for her to be a chump - a CR30 creature should be able to beat a level 14 party effortlessly), but of course you can take what you will out of that.

You made a claim many challenged, based on things people challenged,are you surprised that people on the internet have emotions regarding things they discuss? You seemed to have an emotional response when you stormed away from the game, so... is it really surprising?

Still, I plead that you at least don't equate me studying a point (e.g. in this point whether a party can kill a monster by RAW) to me playing the game. That's a massive disservice. Not that there's any need for us to ever play with each other, but I'd still rather you don't you presume such amount of knowledge without ever interacting with me personally.

We have examples of you discussing pre and during game, this is an odd thing to request imo.

When you're playing a level 14 no magic items core only party banned from using certain spells with no prep at 60' starting distance in an arena she shouldn't even really be able to move in, you have far less margin for error than if you were running it normally... Again, there's more it takes for a CR30 God to be decent than beating a level 14 party with a lot of stipulations and a DM misinterpretation. It might be winnable after that but I'm simply not interested in "btw, you worded this wrong so take 96 damage to the whole party after I randomly force you to start at 60' and in Fireball formation in an unbounded fight" - that's so far from the original point of the thread it's not even funny.

EDIT: To further explain myself, it's obvious after this DF is being an adversial DM and will obviously rule everything against me. I'm not wasting my time on trying to lawyer-proof every single word I write. That's just not worth my time.

hoo-boy this wow.

Please tell me how I'm being an adversarial DM here?

-Was it when I agreed to you spamming divinitations to gain metaknowledge of her statblock?

-Was it when I allowed a massive amount of pregame buffing?

-Allowing 'a 14th level party' to also consist of a cadre of summoned and bound creatures?

-Was it when I was discussing things with you pregame and taking on board your comments?

The game started, you took a turn, didn't like how it was resolved so wanted to start it over.

I have read your own thread DMing youself, where the party just endlessly put walls in front of her breath weapons, ruling that the breath itself doesn't even damage the walls etc.

Oh and that whole line about taking 96 damage after I randomly forced you to do something? starting at 60ft was a pretense of the scenario, if you don't like it don't play to begin with or mention it before the game, don't complain about it to others after the fact and paint me as adversariel because of it.

Your party composition is not convincing to being able to take down Tiamat and your way of playing/DMing just serves your own point more than proving anything.

[N7Paladin]

If Tiamat is really such a chump, one thing going wrong shouldn't matter much, right?

Ooooh I think you'll find this is exactly the case here XD

Snip

You're saying you conceded the removal of context that would render her weaker... But in saying this you're also waving off context that would render your party (usage of resources, probable unavailability of long rest, etc) weaker as well. {Scrubbed}

[BerzerkerUnit]

When you're playing a level 14 no magic items core only party banned from using certain spells with no prep at 60' starting distance in an arena she shouldn't even really be able to move in, you have far less margin for error than if you were running it normally... Again, there's more it takes for a CR30 God to be decent than beating a level 14 party with a lot of stipulations and a DM misinterpretation. It might be winnable after that but I'm simply not interested in "btw, you worded this wrong so take 96 damage to the whole party after I randomly force you to start at 60' and in Fireball formation in an unbounded fight" - that's so far from the original point of the thread it's not even funny.

EDIT: To further explain myself, it's obvious after this DF is being an adversial DM and will obviously rule everything against me. I'm not wasting my time on trying to lawyer-proof every single word I write. That's just not worth my time.

If you felt adversarial DMing was really the issue here, it really shouldn't have mattered in any case bc rd one would really have gone like this:

Druid runs back, readies spell. Mistimes it
Dragon God breathes, party takes a bunch of damage.
Wizard's turn: Forcecage and move away
Everyone else, move away
Begin magic arrow barrages.

This was the thrust of the entire OP. That Tiamat is trivialized by forcecage. If successfully breathing on most party members is a loss condition, she's definitely not a chump. And the emotions raised aren't in response to Tiamat, they're in response to posters appearing hypocritical in the text. It might be miscommunication, but it's more likely the notion that the internet is a place full of faceless voices constantly shouting contradiction and when any of them challenge something one believes or feels, the default response has to be an adamant stance in defiance instead of one prepared for compromise. Even the fruit hanging so low its on the figurative olive branches being sent via pneumatic pipeline underground is ignored, probably because collectively people seem to think the sources of the other posts aren't properly people.

Most have said Tiamat is a tough fight, even with Forcecage in play. Getting a win is a steep climb, doable but with a low margin for error and death as the likely consequence. They have also, in the same posts, admitted that she is not a well designed monster (coming as early as she did in the publication history) and power/flexibility creep of later supplements have made her easier still.

The OP (and maybe other's) insistence that she is trivially easy because some players might have access to one overtuned spell isn't the thing creating emotional reactions, it's the dismissive tone used to insist. It's the unwillingness to recognize that statistically a challenge exists, even if its not the most insurmountable. The equating of "not a statblock that gives the DM carte-blanche to wipe the party" with "mind numbingly simple to defeat" is hyperbolic, its a kind of trash talk, and that's what stirs the emotions.

I've had arguments with some of the worst people about some of the most polarizing topics imaginable and while I've been repulsed by some mentalities and beliefs, I've only gotten angry when A) the belief is something that hurts other people or B) their argument boiled down to "nuh uh" and then smirking as if my inability to change their mind was somehow them winning the argument.

Honey, I don't argue to make people feel differently, I argue to make sure we all understand each other and sometimes that makes people feel differently.

[CapnWildefyr]

Well the results of the first attempt appear inconclusive.

My offer stands for anyone that would like to take it.

If you're trying to test the idea of whether X number of Level 14 PCs can take out a tiamat using a given stat block, arguing over game mechanics for the planned action isn't the best way to do it. I would suggest instead a less adversarial approach -- as in, you are two DMs playing out the same fight. You are not trying to test whether a player/DM correctly states a Ready action, or any other rules, so don't run it like a game. Let all of that go. Ask 'are you trying to do X?' and 'why wouldn't she do Y at this point?' Work out the consequences of each action then erase and try something better/different. You're not trying to beat 1 person, or beat 1 party, or beat 1 avatar, you're testing possible punches and counterpunches. You're trying to run through multiple scenarios with spells and items and tactics. You're not actually playing the game, just talking about playing the game. Just a suggestion.

[Eldariel]

Druid runs back, readies spell. Mistimes it
Dragon God breathes, party takes a bunch of damage.
Wizard's turn: Forcecage and move away
Everyone else, move away
Begin magic arrow barrages./

It wouldn't matter except in this case Tiamat was made 450'/150' so she's not gonna fit in Forcecage or any kind of obstacle (frankly, she shouldn't even be able to manoeuvre in the arena we had but whatever). DF wanted to "test" her without Forcecage; it's kind of a given that if she fits in, it's enough to take her out. The only challenge is to have enough damage to overcome her Regeneration after that, which most level 14 parties should manage (especially if not going with "no magic items PHB only" like I did - adding Holy Weapon, Summon Celestial, Summon Undead, Summon Aberration, Tenser's Transformation, etc. to the buff pool makes it quite easy to buff the party Fighter/Ranger enough to kill it, or create something that can kill it).

But that's not interesting nor something worth playing out. The point of playing it out was to test the hypothesis of her being beatable regardless of size on level 14, which I maintain is the case. She's not easy that way but if you can beat her at all on level 14, I would definitely argue she's way too weak to be a CR30 (Deadly x 7 or something) threat. Again, it wouldn't be hard to rework her to be a more viable threat but as it stands, inability to deal with force constructs in addition to lack of good mobility options (even just Legendary Action "move" would be a huge improvement) and inability to deal with magical obstacles more broadly hurts her more than it should. On level 14 she may be rough but level 15 adds 8th level spells and the adventure can end on that level too and she should be more than a match for a level 20 party, which I really doubt.

[JNAProductions]

It wouldn't matter except in this case Tiamat was made 450'/150' so she's not gonna fit in Forcecage or any kind of obstacle (frankly, she shouldn't even be able to manoeuvre in the arena we had but whatever). DF wanted to "test" her without Forcecage; it's kind of a given that if she fits in, it's enough to take her out.

All she needs to be is more than 20' in any given dimension to prevent Forcecage from working.

A Huge Storm Giant is 26' tall. Why would the Gargantuan Queen Of Chromatic Dragons be smaller than that?

[Eldariel]

All she needs to be is more than 20' in any given dimension to prevent Forcecage from working.

A Huge Storm Giant is 26' tall. Why would the Gargantuan Queen Of Chromatic Dragons be smaller than that?

Not the point. The book just gives her no dimensions, just size category, and I'm specifically talking about the RAW there. I've yet to see a good argument for why RAW she'd be anything but 20'/20'. Given her shape, the idea that she'd be taller than she's long also seems suspect. But anyways, that's trivial: whether or not you accept the premise, the fact that she's in general vulnerable to getting Force Walled in is pretty sad for a God.

[Dork_Forge]

If you felt adversarial DMing was really the issue here, it really shouldn't have mattered in any case bc rd one would really have gone like this:

Druid runs back, readies spell. Mistimes it
Dragon God breathes, party takes a bunch of damage.
Wizard's turn: Forcecage and move away
Everyone else, move away
Begin magic arrow barrages.

This was the thrust of the entire OP. That Tiamat is trivialized by forcecage. If successfully breathing on most party members is a loss condition, she's definitely not a chump. And the emotions raised aren't in response to Tiamat, they're in response to posters appearing hypocritical in the text. It might be miscommunication, but it's more likely the notion that the internet is a place full of faceless voices constantly shouting contradiction and when any of them challenge something one believes or feels, the default response has to be an adamant stance in defiance instead of one prepared for compromise. Even the fruit hanging so low its on the figurative olive branches being sent via pneumatic pipeline underground is ignored, probably because collectively people seem to think the sources of the other posts aren't properly people.

Most have said Tiamat is a tough fight, even with Forcecage in play. Getting a win is a steep climb, doable but with a low margin for error and death as the likely consequence. They have also, in the same posts, admitted that she is not a well designed monster (coming as early as she did in the publication history) and power/flexibility creep of later supplements have made her easier still.

The OP (and maybe other's) insistence that she is trivially easy because some players might have access to one overtuned spell isn't the thing creating emotional reactions, it's the dismissive tone used to insist. It's the unwillingness to recognize that statistically a challenge exists, even if its not the most insurmountable. The equating of "not a statblock that gives the DM carte-blanche to wipe the party" with "mind numbingly simple to defeat" is hyperbolic, its a kind of trash talk, and that's what stirs the emotions.

I've had arguments with some of the worst people about some of the most polarizing topics imaginable and while I've been repulsed by some mentalities and beliefs, I've only gotten angry when A) the belief is something that hurts other people or B) their argument boiled down to "nuh uh" and then smirking as if my inability to change their mind was somehow them winning the argument.

Honey, I don't argue to make people feel differently, I argue to make sure we all understand each other and sometimes that makes people feel differently.

Slow clap well said

If you're trying to test the idea of whether X number of Level 14 PCs can take out a tiamat using a given stat block, arguing over game mechanics for the planned action isn't the best way to do it. I would suggest instead a less adversarial approach -- as in, you are two DMs playing out the same fight. You are not trying to test whether a player/DM correctly states a Ready action, or any other rules, so don't run it like a game. Let all of that go. Ask 'are you trying to do X?' and 'why wouldn't she do Y at this point?' Work out the consequences of each action then erase and try something better/different. You're not trying to beat 1 person, or beat 1 party, or beat 1 avatar, you're testing possible punches and counterpunches. You're trying to run through multiple scenarios with spells and items and tactics. You're not actually playing the game, just talking about playing the game. Just a suggestion.

This is the second time I have been labeled as adversarial, how is what happened adversarial? How is any of the prep and discussion in the run up adversarial?

Here's a thing, we were playing the game, we were explicitly playing out the scenario to see what happened, both sides being the DM in that situation is problematic, why? See Eldariel's thread Dming themselves where readying a wall neuters Tiamat's Legendary actions, despite it not being clear RAW.

If the reason the party loses to Tiamat is player error, then at minimum that shows that she's clearly not that easy to defeat and said player shouldn't be so adamant about it.

It wouldn't matter except in this case Tiamat was made 450'/150' so she's not gonna fit in Forcecage or any kind of obstacle (frankly, she shouldn't even be able to manoeuvre in the arena we had but whatever). DF wanted to "test" her without Forcecage; it's kind of a given that if she fits in, it's enough to take her out. The only challenge is to have enough damage to overcome her Regeneration after that, which most level 14 parties should manage (especially if not going with "no magic items PHB only" like I did - adding Holy Weapon, Summon Celestial, Summon Undead, Summon Aberration, Tenser's Transformation, etc. to the buff pool makes it quite easy to buff the party Fighter/Ranger enough to kill it, or create something that can kill it).

But that's not interesting nor something worth playing out. The point of playing it out was to test the hypothesis of her being beatable regardless of size on level 14, which I maintain is the case. She's not easy that way but if you can beat her at all on level 14, I would definitely argue she's way too weak to be a CR30 (Deadly x 7 or something) threat. Again, it wouldn't be hard to rework her to be a more viable threat but as it stands, inability to deal with force constructs in addition to lack of good mobility options (even just Legendary Action "move" would be a huge improvement) and inability to deal with magical obstacles more broadly hurts her more than it should. On level 14 she may be rough but level 15 adds 8th level spells and the adventure can end on that level too and she should be more than a match for a level 20 party, which I really doubt.

You agreed (and self imposed entirely on your own) anything that could remotely be a nerf to the party in the circumstances.

If the 'party' (two of which had resistance and one of which is a Life Cleric) can not tolerate being breathed on once then what are you proving? By trapsing in with a bunch of summons what are you proving about a level 14 party? That adding medium CR creatures to a player party is a buff?

You utterly failed to demonstrate how the statblock as written could be handled by a party of 14th level unless things went your way, against the rules, RAI and ruling of a DM.

[JNAProductions]

Not the point. The book just gives her no dimensions, just size category, and I'm specifically talking about the RAW there. I've yet to see a good argument for why RAW she'd be anything but 20'/20'. Given her shape, the idea that she'd be taller than she's long also seems suspect. But anyways, that's trivial: whether or not you accept the premise, the fact that she's in general vulnerable to getting Force Walled in is pretty sad for a God.

RAW is that she controls a minimum of a 20' by 20' area.

If I have my PCs roll for HP, am I justified in saying they gain 1+Con Mod HP because that's the minimum they can gain? That's similar to what you're saying with Tiamat's size.