There's no use casting the gate under the doomsday device until the timer's paused, in case it settles instantly, so it may be several days before kaboom.
Contessa, Doormaker and the Clairvoyant, a backup copy of Dragon, Nilbog (who is delighted to be brought to Fairyland and even more delighted that Promise, of whom he is so fond, has "inherited" its rulership from its Queen, and who can construct armies and send them through gates without having to be personally fielded), and Bitch (to assist Nilbog) are all brought through to the Fairyland colony as a safety/reserves measure.
Promise wonders to Cauldron if she should try talking to Scion while waiting for the gate to settle, if it's not instant. In case this distracts him or something in a useful way.
Cauldron is also preparing to go public to the cape world. It'll drastically decrease their own power, but that was never the goal. The battle against Scion will either begin or end when that gate settles, and if they have to fight they'll need soldiers. Top members of major hero and villain groups will be invited to hear the news on a potential S-class threat worse than the Endbringers, and can likely be talked into helping to stall him. It won't be just Dragon and Nilbog, if it comes to a fight.
It would be, but it's also just about the least neutral ground imaginable for a truce meeting. Anywhere else can be attacked, but it'd be the single most defensible group in existence. Probably some players will want to send people afterward, if she makes the offer.
They have a booth for each group, lit from the back panel so everyone appears to everyone elsewhere in the circle as a silhouette. It's all very dramatic probably. It's technically anonymous, but some are instantly recognizable. There's the Triumvirate representing the Protectorate, Narwhal and one of the newly plural Dragons for the Guild, Nonpariel and Agnes Court for the Elite, Moord Nag for Moord Nag and Adalid for Adalid. The Suits have indistinguishable representatives, as do the King's Men, the Yàngbǎn, and other even less recognizable groups. Anyone who might be accurately described as a Power. One of the spaces is set aside for Promise and her choice of Kept. (The Undersiders have a seat, either because they deserve it or because relocating Bitch had to involve telling them enough that they could insist on the full story. Every other faction can assume it's the first one.)
The Doctor informs her audience that Glaistig Uaine was not invited because of her unwillingness to work with the others on this, and that the Three Blasphemies declined to come. That little combination earns everyone's attention.
Cauldron's side is one of the less identifiable ones. Promise can recognize the Doctor, Contessa, and the Number Man, but to anyone who hasn't already met them they could be anyone. They introduce themselves only as Cauldron. Apparently confirmation of Cauldron's existence is a revelation for a substantial fraction of the people present. The Triumvirate plays along.
And then the Doctor provides exposition.
Many people don't believe it at first. After all, the main evidence comes from a precog who can no longer check the relevant things. Cauldron clearly believes it enough to sacrifice their secrecy for cooperation just in case the assassination attempt fails, but that doesn't make them right. Some (mainly heroes) even want to warn Scion, though as unresponsive as he is no one would know if it worked. Others, especially of the less than heroic persuasion, ask why they would fight if Scion is as unstoppable as Cauldron says. Or why to fight him now, rather than waiting until the last minute, since he is still routinely stopping disasters.
But Cauldron has information, and Contessa can be very convincing when deploying it. It helps that the Triumvirate can conspicuously become convinced at an opportune time, and for all Promise can tell they similarly have agents in every other group. There are frequent arguments between factions, but Cauldron keeps control of the situation. They don't bother with irrelevancies like their own crimes.
Some of this debate is directed at Promise. A new and powerful villain who is integral to the killing Scion plan as well as the only method of access to the one place he can't reach. Many suspect she's in Cauldron's pocket rather than the other way around, and more than a few are wary of being in a room with her.
Promise's bodyguards are invisible, because she likes the combination of increased and decreased intimidation factor. If anyone goes so far as to actually suggest that she's in Cauldron's pocket, that will be interesting; so long as it confines itself to obvious suspicion she won't dignify it with a response.
The eventual consensus is more or less what Promise and Cauldron talked about earlier. Drop the doomsday device on Scion, and if the gate takes time to open Promise can try talking to him. One of the Suits asks her whether there are other fairies who would do the same, since no one knows how long it would take. And if any part of this results in Scion starting to kill everyone, Cauldron can provide transportation to the scene of the fight with their Scion-proof portal network. The Protectorate's handful of gates has been officially outdone.
Moord Nag says that she will help fight if necessary, in exchange for five thousand lives fed to her pet. The Doctor is prevented from immediately agreeing because of Promise's orders, but that doesn't mean she and the Number Man can't try to convince the others that it's an acceptable trade.
Promise would like to know where, exactly, anyone proposes to get five thousand lives for Moord Nag's pet.
The Number Man answers. "The first land mass he shatters, before all the survivors drown. With our portal network occupied bringing in defenders, there will be no shortage of people who cannot be saved. And Moord Nag may be able to stall Scion long enough to prevent the second land mass by herself. An exact answer would depend on Scion's chosen method of mass destruction if it comes to a fight and on how quickly the scavenger can travel."
Eidolon takes his lead from Alexandria and stays silent, but Legend says "Absolutely not" and most of the heroes in the room back him up.
"Declining her offer risks condemning millions," the Doctor insists. "At least."
Promise avoids looking speculatively at Moord Nag. "Does it strictly have to be deaths?" she inquires. "Of humans, in particular? Not the already-deceased; not sacrificial Nilbog creations; not some kind of mild inconvenience for some number of fairies...?"
(The heroes, and most villains too, are pretty okay with the idea of Moord Nag not becoming vastly more powerful.)
"It seems worth checking the other possibilities. I am sure I can borrow some sub-sapient construct and locate a suicidal fairy if the tests interest you."
"If there is a fight," the Doctor reminds everyone. "Keep in mind this is a condition within a condition." Somehow no one is reassured.
She continues working on Moord Nag's name. Possibly to be held in abeyance until after kabloom, but it will be nice not to have to hunt for it in the moment if something comes up.
"Some of us need more preparation than others. The Protectorate's tinkers can hardly fight Scion in their everyday equipment. Shall we make it a month?"
"That kind of delay would risk the public finding out. Or worse, Scion," says a woman wearing a gauntlet so red the color is visible in silhouette. "And if Cauldron is to be believed about the number of worlds at stake, any chance of that can tip the scales."
"There's going to be some tradeoff between preparedness and immediacy; the question is where on the spectrum between 'not even bothering to hold this meeting' and 'just waiting for Scion to attack first' it should be. How much of a difference will a month make, here, for what percentile of Tinker? Low-grade Taught won't make a difference with a year to work; String Theory may have rendered everyone else redundant with a week; what's the median and what would they be accomplishing with their time?"
"Call it a week for the stronger tinkers to refurbish or rebuild what they used for Endbringer fights, two months for the vast majority to start from scratch and finish any weapon they can build. The other factor, as Rukavitsa says, is that this endeavor is no longer secret. When it gets out to the public, we can expect widespread panic, and there will be something Scion can pick up on."
"He could have picked up on us having this conversation or String Theory building her doomsday weapon or Cauldron having existed to oppose him. If the panic can be kept to a low hum of conspiracy theory - selectively informing the handful of best tinkers, perhaps, and only allowing a week or two, not months - it seems unlikely to exceed whatever threshold he's using."
"We did ask for representatives for a reason. We need numbers in any fight, and there are teams here, not individuals.
After leaving, tell only people who would benefit from preparation, and only if they would do the same. It is laughably unlikely to keep a secret for any length of time, but a head start on preparation over publicity is the best we can hope for."
"Where should I bring test subjects for you?" she asks Moord Nag.
Most groups don't leave. Some factions had unofficial agreements with each other against escalating in firepower, and are discussing suspending them. Others ask Promise about Fairyland's availability either as a place to hide from Scion or as a place to attack him from.
Fairyland is available as both things. For security reasons, Promise needs to believe that she could if necessary evict or contain anyone who would like to enter it unless they seem impeccably trustworthy somehow.