"I am a little hard to bribe," Cam points out.

"The Valar are magic. They probably have lots of things you can't just reproduce."

"All of which I'm doing fine without."

They wait outside the walls and someone eventually emerges to talk. 

"Hello. I have an experiment I'd like to perform regarding Maiar and illusions, to see if I can verify the genuineness of oaths. Is Melian willing to help?"

"What's the experiment?"

"I'd like her to produce and record some illusory words - it doesn't particularly have to be an oath - and then ideally a sentence of mixed real and illusion words, and I'll see if I can conjure the recordings based on certain parameters. I can provide the recording device if that helps."

"She says that she'd be happy to produce and record some words if you provide a recording device."

Cam hands one over. "Hold red button to record, release to stop."

He takes it gingerly. "And it doesn't do anything else?"

"That is absolutely all it does. Although I hear there's a Brithombar ambassador in there and if they'd like a phone I can provide."

"No, thank you. We'll get back to you when Melian's checked this."

"Sure. Can you give me an idea of how long that may take?"

"It could be a few hours." 

"Okay." Would his diplomatic escort like lunch and playing cards or something while he drinks coffee and reads things?

They would! They can make it a sort of picnic in the shade of the giant concrete wall. 

Fun.

He reads things. He texts Maitimo that results are pending, and Fëanáro (encrypted) what his idea was.

Fëanáro replies that he should, if he's considering it at all, demand from the Enemy oaths to the effect that the parley isn't a distraction to keep Cam in one place while they try something in addition to the obvious ones about being non-lethal and non-injurious and no lies spoken and so on. He thinks it could be worth it, and says so. 

Cam would very much appreciate consultation on the exact wording to solicit. He is thinking of raining letters on Angband and requiring that the oath be recorded and verifiable in advance.

He sends annotated suggestions. 

I swear that in this negotiation I am using all words' standard referents, do not expect confusion over the referent of any spoken word, have not made an effort to create such confusion, and am speaking entirely in Quenya. I will not use oaths, memory alteration, or any other means to deliberately alter my expectations, and as far as I know I have not done so. Forces under my command do not have explicit or implicit orders to use the parley to advance any military objectives. If we agree to a ceasefire for the duration of the parley I expect it to be obeyed on my side and I will prevent violations of a ceasefire on either side from escalating. For the duration of the parley I will not lie. I will not prevent any participant in the parley from departing. I will not use any oaths, magic or technology to affect any participant in the parley. I do not have chip- or mind-reading capabilities beyond the known-to-you ability to upload a chip. I will not harm anyone at the parley. I will not take actions that cause anyone at the parley to be harmed.  I expect that all participants in the parley will return home unharmed. There is no major information or strategic planning pending that would alter that expectation. None of my people have orders to interfere with the parley. If they had such orders I would know of them. Coming to parley will not put you in a strategically disadvantageous position compared to verifiably having managed never to receive the invitation. So I swear.

That looks pretty good to Cam. Maybe "I would be able to find out if I had done so, have made a good-faith attempt, and have determined that I did not" on the expectations thing? Should Cam expect to need to privately communicate with people on his side at the parley, should there be an added thing about not having a way to read over people's shoulders?

Oh, right, Cam doesn't have osanwe. Yes, those are both good additions. 

Cam folds them in. And maybe the word should not be 'home'. Cam lives in Hell.

They can just say 'to return', probably. Perhaps he should send the note with instructions about how the Enemy should respond: slightly misleading instructions like 'type your response into any computer console with the filename 'parley-negotiations' and I will be able to retrieve it', just in case the Enemy doesn't yet realize that Cam can get anything committed to physical form.

Sounds good. And will Cam likely need to provide an audio recorder for the oath itself? Seemed like Melian didn't have any.