Leareth, who is kind of stuck right now and glad of a break, greets Vanyel with surprising warmth and explains the spell. He asks Khemet's researchers if they can supply black carbon or coal or something for Vanyel to try compressing, and also do they have any shielded rooms for practicing magic in? This seems like the type of test where if it goes badly something might explode, and Leareth can provide shielding too but Vanyel is five to ten times as powerful as he is. 

They can absolutely supply black carbon and coal, and they do have shielded practice rooms, this being a hazard of their kind of magical experimentation too. Nefreti Clepati infamously levelled the temple of Nethys once. (Nethys infamously rewarded her with several more cleric levels for it.)

Vanyel takes a pile of black carbon and coal into a practice room, and shoves it into an approximate sphere with the barrier-spell, and then tightens the force-net as instructed - and pushes power into it - and more power - there's a node within reach and he reaches for it and feeds more and more power– 

The ball shrinks and compresses and glows - 

- and then the spell, strained past its limits, violently explodes. 

Leareth only has to shield both of them from one angle, since Vanyel is standing close to the door, and he does so while also using magic to yank Vanyel back and slam the door shut. 

"...Oops." 

"Healing?" asks one of the magic researchers with cleric levels who is standing nearby.

"I think I'm fine - except for the part where I have a horrid backlash headache, ow." 

"I think that Lesser Restoration would probably address that." Leareth frowns slightly. "I suppose I had better invent you a spell that can take more power. I think you were getting there but you need a technique that can handle more power input." 

"I hope it doesn't inconvenience anyone that I drained that entire node– ow. I hate having magic explode in my face." 

The cleric casts Lesser Restoration. If anyone is annoyed by the node being drained they don't say so. 

"By rights the possibility ought to make diamond prices considerably lower," someone is murmuring to someone else. 

"Only if people with the information are allowed to trade on it. I don't think it's a way to get us cheap diamonds quickly enough for the war."

"Not a lot anyway, even if Leareth gets this tomorrow, it's really tiring. Also I have further coordinating to do in Velgarth so I'll be leaving in the morning." 

Leareth looks like he poooossibly wants to object to this, but instead just nods. 

Once the other group has asked all their questions he tells them that he'll be ready to Gate them to the requested location tomorrow morning, and heads back out. Servants can show them to guest rooms and shielded meeting rooms for any further planning they want to do.

Keiran and Callia want to look at maps and go through their list of Heralds and numbers for the Guard, and draft messages from the code-book Katha gave them to send back to Valdemar by crystal ball in the morning. 

Vanyel figures he's done enough meeting and discussing. He goes to bed. 

Leareth, back with Nayoki, has what he thinks is their first breakthrough on Velgarth Gates - which is that they can route the search part of the spell through one or more of the elemental planes, without actually having the Gate land there. If they're right and Velgarth shares the same elemental planes with Golarion, then if they go 'through' the spell ought at some point be able to find it. 

He demonstrates a tiny test Gate on two hand-sized practice thresholds across a table from each other. Notes that it has the surprise plus of, he suspects, also being untraceable - even if a mage is directly watching one terminus, they won't be able to follow the threads of magic to where the other one is.

Leareth is delighted! He's tempted to go find Khemet and tell him right away, but 'go find the pharaoh' is probably a huge breach of protocol, so instead he just asks one of the servants if Khemet is still available. 

The servant goes off to check. The pharaoh comes by a few minutes later.

"We have the first step toward an inter-world Gate." Leareth casts it again, quickly explains the magic, all while looking very pleased about it. "I am much more confident we will have this working in time." 

"Oh, excellent!"

(Leareth really appreciates talking about Velgarth magic - or anything really - with Khemet, who has zero context on it and is nonetheless smart enough to follow easily.)

He takes the Gate down. "Unfortunately it is more tiring than an ordinary Gate, which will present a greater difficulty if we wish to move thousands of people, but - once the spell exists I can teach it to others. I think we can make it work." 

"Have we tried having someone stand by and cast fatigue-combatting spells on you while you do tiring things? I would be curious if they can keep up with the tiredness that way or if eventually you run out of something the spell isn't quite addressing."

"Lesser Restoration is quite effective on backlash but I have not tested continuing to do tiring work for a long time while having it cast repeatedly. It does seem worth trying. If someone is available to cast fatigue-combating spells now, it will not matter much if I do end up exhausted since I am going to bed after that." 

He waves someone over. 

Hmm, what's the most tiring but still non-destructive magic he can do...? Leareth settles on repeatedly raising a very big un-scaffolded Gate from where he is to his bedroom and taking it down again; holding a Gate is easier than raising one, and un-scaffolded uses a bit more power than putting a Gate on a doorway, not normally enough to be that significant but if he's going to do it twenty times in a row it'll add up. 

...He's going into it kind of tired already, after working all day, and despite the short range, he's tired enough after the third one that he kind of wants to sit down. He nods to the cleric who's going to cast the spell for him.