"I can write things down but it's much much slower than somebody being able to ask me questions and stuff, I don't know what they're currently working with or what they need. Do you not have channels for parley open?"

Urtho makes a face. "In theory. I'm - not incredibly comfortable sending you. The problem is that their army uses compulsions - er, mind-controlling magic. They claim there are rules about it, and using it on an emissary would be against them, but - it would be a huge temptation, right, to kidnap you and force you to work for them..." 

"No, you absolutely shouldn't send me into a war zone, I'm the only copy of Sing's seed instructions anywhere! I was thinking I'd get relayed conversations."

"...We can do that. I would rather not risk a Mindspeaker either, which is why I thought writing might be easiest, but I suppose we could have a Mindspeaker relay from off site." 

"I can try with writing but it's less dynamic. Responsive. Too easy to offend someone and not notice till too late."

Urtho nods seriously. "I'm not sure if taking offense is what I expect to go wrong, exactly, but it's certainly been - difficult to communicate with Predain. It - would be good to avoid more misunderstandings." 

"Maybe... do you have, uh - maybe I could build a not magic communications thing, but the problem with it is that you can build a listener easily but not a sender, so it only works one way if you don't have enough cooperation to do more than give them a little listening thingy."

Urtho, distracted briefly from the unhappy matter of the war toward the much happier question of artificing, briefly lights up before trying to control it and look appropriately solemn for the situation. "Incredible? How does it work? We do have magical artifacts for communication, but they are not secure like Mindspeech is, messages can be intercepted or even altered..."

And Ma'ar would claim he wouldn't do something like that, just like he claims he wants peace, but - he could. He's very very good at magic. 

"- oh, well, if that's the problem you can solve it with math and a letter!"

Urtho blinks. “That sounds fascinating! Say more? What sort of math?”

(It’s belatedly occurring to him that it would be fairly bizarre in the first place for Ma’ar to tamper communications from his own side, since if he wanted to be misleading he could just…tell the emissary what to say… There’s just still the mental habit of anxiety that Ma’ar will always outthink him and turn his plans against him…)

Tarinda can with Page's invisible assistance rattle off quite a good explanation of the relevant cryptography for her understanding of their comms situation. It involves prime numbers and stuff.

Urtho listens raptly! It's not entirely clear how well this solves any of his most pressing actual war-related problems, but it’s fascinating! 

…Aaaand after that he really does need to go, the hertasi have been trying to get his attention for a while. He can arrange for artificers to come meet with Tarinda and get instructions on what she’s going to need to start making her world’s thinking machine - unless she needs to rest now, in which case the hertasi can escort her to a room - and he’ll work on setting up a parley with Predain and alert her immediately once that’s been arranged?

She doesn't need to rest right now! She can put in materials orders - or, first, discover at what granularity she needs to put in the materials orders, at any rate - with the artificers first.