<Those all sound like things that would make them hard to get to, yes. 

My current best assessment is based on very little information still and the situation probably merits more, but it seems like several features of this world including the widespread mindreading and the very low tech level mean that taking this world by infiltration would not be a good use of resources for the Yeerks, and they are much likelier, were they here, to just try to take it by violence - land an army somewhere, spread it out enslaving people to add to it. Would you have heard of it if it were happening very far away?>

:It's remotely possible Valdemar wouldn't have, if it were really far away and in the last year or two. I'm almost certain Leareth would know, though, if it were on this continent. He - likes to know things: 

<He said he thought he would know, yes. And he did not consider it likely.> His tail swishes. <We will accept your offer of refuge in Valdemar, I think. However, our starship is buried north of here, stuck in the ground from the impact; were we to leave it there Leareth could doubtless learn a great deal from it. Would magic make it possible to move? It's very large, and can move under its own power only when in better condition than it is presently.>

:...I would have to see it, I think. Maybe: He grimaces. :Leareth could absolutely do it. We're - not as advanced as he is, magically speaking, and I don't think any of us could Gate something that big. We can probably support some of its weight? If it's able to fly with some help: 

<Right now it cannot fly at all but we should have the resources to fix that eventually. Hmmm.> Tail-swish. <Can your magic be used to travel between planets.>

:Not that I know of. I mean, theoretically if you'd been to both places you could Gate? I just expect the power requirement would be intractable, Savil is our strongest mage for Gating and she struggles with more than four hundred miles: He looks down. :Sorry: 

<We can repair the ship. It's just repairing the ship without giving your acquaintance the conquerer - not the knowledge to build the ship, it relies on some things that have fairly extraordinary prerequisites and aren't observable from the exterior at all, but the knowledge to conquer your world, that I'd worry about.>

Vanyel makes a face. :The stupid thing is that he would absolutely help if you asked him. He'd just - right, afterward he'd know more than enough to conquer the world if he wanted: Sigh. :I - think your war with the Yeerks might be a higher priority than Leareth maybe getting some information on your technology, though. It sounded time-sensitive: 

<It is time-sensitive. It is possible I will decide that unleashing a different conquerer on the galaxy is worth it if the Yeerks are defeated, but - it is not a decision I want to make half by accident. What I'd like to do is get to Earth and get a sense how bad it is, which would change how much we're willing to risk in responding. But probably I will have to make the decision without knowing that. 

What can mages do. He offered us several hundred of them.>

:Several...hundred...: Vanyel has to spend a moment collecting himself from the shock. :I, um, for reference, we have about a dozen. Mages can do combat, really effectively - fire, lightning, barriers, other more complicated techniques. Set wards and traps. We can shield things. We can scry and see what's happening far away, and communicate or travel instantly across long distances, well, where 'long' is hundreds of miles, not the distance between planets. Also mages who are willing to do so can - control other people with compulsions. Valdemar doesn't do it but I bet Leareth's people would, it's obviously very effective for spying or infiltrating some group. Then there are other Gifts - Mindspeech and Thoughtsensing are their own Gift, we use that for fast communications within Valdemar. Farsight is what it sounds like, imitates scrying. Fetching can move or teleport objects...: 

He goes down the entire list of known Gifts. 

<Our scout was flying over the forest about five miles from our starship when something suddenly seized control of him and forced him to land without communicating with any of us. That's - compulsions?>

:Yes, that sounds like a compulsion: Shiver. :I've never cast one or experienced one, though: 

<Andalites consider the thing that Yeerks do - and associated things, even if they are done by other means - to be a great evil.>

:I'm not going to disagree on that. Leareth would say most evils can still be justified in the right circumstances, I guess, but... It'd make sense if that left you unwilling to work with him, even setting aside the technology question:

Internally he's thinking this isn't that different from his own use of magic to trap a scout and Truth Spell plus Thoughtsensing to question them. He doesn't say that either. 

<I would work with Yeerks if they were for some reason on my side and I could trust that. I - do not immediately know how I would verify that I could trust that. However it sounds like Leareth could easily have left us with no choice but to make the ship self-destruct with most of our people in it so I am grateful that he did not decide to do that.>

:Oh, if he'd, what, tried to steal it, or to control someone into taking him there...: Vanyel shakes his head. :He probably wanted the same information we did back in Haven, if he spotted you arriving. And we - I...: What is he even supposed to say. :I'm sorry for, er, how I treated your scout. We were really panicked: The Truth Spell must have also made them think of Yeerks. 

<You were at war, and observed something strange. If you had tried to scout in our home world it would not have gone any better. 

You should know that we cannot safely remain in a morphed form for more than a few hours, and that if prevented from demorphing when it is necessary we get stuck.>

It takes Vanyel about five seconds to catch the implications, and another ten seconds to go from 'internal screaming' to formulating any sort of response. 

:Oh - gods - did I - I knocked them out for half a candlemark, did they - are they...?: 

<He cannot demorph, yes. Obviously we do not blame you.>

Vanyel barely hears that because he is busy absolutely blaming himself. :I'm so sorry, I - gods...: 

:Van. Stop it: 

Vanyel takes a deep breath, and tries to calm down. Focus. :Er, is that something we could maybe - try to fix, with magic? I don't know how morphing works but Savil was in range when some of your scouts did it, she said it looked like things moving around between other planes, which means our mage-sight can sense some of it: 

<...huh. I have no idea. If you could, or if you could extend the range that can safely be spent in morph, that would be extraordinarily valuable to us. It involves storing the original body and mind in z-space and maintaining a link to a construct-body, copied from a creature we have been in contact with in the past. The length that the link can be safely maintained depends on the mass of the person morphing but for a typical Andalite is a few candlemarks.>

Unfortunately this is yet another area where Vanyel is confident Leareth could figure it out much faster than he can, and obviously Leareth absolutely shouldn't be given a chance to study morphing if they want him to not take over the world. :That's fascinating. It looked like that, to me, I thought it was a summoned creature from another plane with a construct-body built here, only it wasn't magic. Anyway, we can help you study it and see if we can improve it: 

<Thank you. Do you want to come see the ship so you can give me your estimation of our prospects of moving it with magic assistance? It is perhaps fifty miles from here.>