"There is," he says to the demon, "a way to travel between worlds without being summoned. I will trade you the knowledge of how to make it for three of them and some help identifying a habitable planet in our new dimension."
"It might not work, it seems worth trying. This ship's now in orbit over our new habitable planet. You want to go get spellbinders next. Not the Bell, they'll never stop chasing you if you take the Bell and she's indestructible anyway, but at least fifty others, you need thirty-six for indestructibility and I don't know if all of them can learn the charts. I am going to go move my kingdom somewhere out of their way while you do that."
"You should but you may run into timing problems there, I doubt it'll take more than a few hours for your hosts to be noticed missing and once they are they'll definitely conjure for Yeerks in known dimensions who aren't in your native universe. ...is it too late for you to impersonate your host, or is he spending too much time around people with flat Elf osanwë -"
"All right. Now, as it stands, if they fork your hosts to try to use them to follow us to the new dimension I don't think they'll get anything, you didn't see the dimension we passed through. You should probably always use me or the Hork-Bajir hosts as your ride through that intermediate dimension, unless you've got a way of making sure the hosts can't see anything that'd let them identify the dimension for targeting."
He sends a mental image of the lightleaper he parked in the intervening dimension to the Yeerks and not their hosts. "All right. I will meet you back here once I've moved my kingdom. I'll be identifying people who will make suitable hosts, do you have Yeerks who can be agreeable enough towards their hosts that an Elf I order to cooperate is likely to not die?"
"Willing to at least pretend to adopt a posture of 'I am impressed with you and it speaks well of you that your King chose you for this, we are allies working together', willing to let them sing occasionally. I think that'd be enough to keep someone alive indefinitely but it's probably the minimum."
"Great. I can also less complicatedly get you humans. Good skill." And off to Shadow.
When they reconvene they have a bunch of baby Yeerks in the shipboard tank, some future daeva and some future spellbinders.
And Shadow has been hopped minus its Valar - Edda - Space - Hell - Revelation - Buffer - to their new dimension. It survived the jump wholly intact and without its sun and moon at all inconvenienced, what with them being flying fruit.
"Has anyone checked that we're not accidentally adjacent to any of the peal's known worlds?"
"Great. Do you all want to come live in Shadow, which I'm renaming Independence, for the time being? Once you have daeva you can make planets more suited to your needs, but for now -"
Pop. "These are my people. I would be delighted to provide hosts in the spirit of this alliance, but if you take them without my leave that would damage the trust between us. Unrelatedly, your host's crying and shrieking is likely to be vaguely upsetting to everyone within ten miles."
"None come to mind."
"Yes, certainly, unless you think you have less than a day left."
"Do you have preferences for Elf or human?"